indexing
	description: "Linear widget container.Base class for EV_HORIZONTAL_BOX and EV_VERTICAL_BOX"
	status: "See notice at end of class"
	keywords: "box, container, child"
	date: "$Date$"
	revision: "$Revision$"

deferred class interface
	EV_BOX

feature -- Initialization

	frozen default_create
			-- Standard creation procedure.
			-- (from EV_ANY)
		ensure then -- from EV_ANY
			is_coupled: implementation /= void
			is_initialized: is_initialized
			default_create_called_set: default_create_called
			is_in_default_state: is_in_default_state
	
feature -- Access

	accept_cursor: EV_CURSOR
			-- Result is cursor displayed when the screen pointer is over a
			-- target that accepts pebble during pick and drop.
			-- (from EV_PICK_AND_DROPABLE)
		ensure then -- from EV_PICK_AND_DROPABLE
			bridge_ok: Result = implementation.accept_cursor

	actual_drop_target_agent: FUNCTION [ANY, TUPLE [INTEGER, INTEGER], EV_ABSTRACT_PICK_AND_DROPABLE]
			-- Overrides default drop target on a certain position.
			-- If Void, Current will use the default drop target.
			-- (from EV_WIDGET)
		require -- from EV_WIDGET
			not_destroyed: not is_destroyed
		ensure -- from EV_WIDGET
			bridge_ok: Result = implementation.actual_drop_target_agent

	background_color: EV_COLOR
			-- Color displayed behind foreground features.
			-- (from EV_COLORIZABLE)
		require -- from EV_COLORIZABLE
			not_destroyed: not is_destroyed
		ensure -- from EV_COLORIZABLE
			bridge_ok: Result.is_equal (implementation.background_color)

	cursor: EV_DYNAMIC_LIST_CURSOR [EV_WIDGET]
			-- Current cursor position.
			-- (from EV_DYNAMIC_LIST)
		ensure then -- from EV_DYNAMIC_LIST
			bridge_ok: Result.is_equal (implementation.cursor)

	data: ANY
			-- Arbitrary user data may be stored here.
			-- (from EV_ANY)

	deny_cursor: EV_CURSOR
			-- Result is cursor displayed when the screen pointer is over a
			-- target that does not accept pebble during pick and drop.
			-- (from EV_PICK_AND_DROPABLE)
		ensure then -- from EV_PICK_AND_DROPABLE
			bridge_ok: Result = implementation.deny_cursor

	first: like item
			-- Item at first position
			-- (from CHAIN)
		require -- from CHAIN
			not_empty: not is_empty

	foreground_color: EV_COLOR
			-- Color of foreground features like text.
			-- (from EV_COLORIZABLE)
		require -- from EV_COLORIZABLE
			not_destroyed: not is_destroyed
		ensure -- from EV_COLORIZABLE
			bridge_ok: Result.is_equal (implementation.foreground_color)

	has (v: like item): BOOLEAN
			-- Does chain include v?
			-- (Reference or object equality,
			-- based on object_comparison.)
			-- (from CHAIN)
		ensure -- from CONTAINER
			not_found_in_empty: Result implies not is_empty

	has_recursive (an_item: like item): BOOLEAN
			-- Does structure include an_item or
			-- does any structure recursively included by structure,
			-- include an_item.
			-- (from EV_CONTAINER)
		require -- from EV_CONTAINER
			not_destroyed: not is_destroyed

	help_context: FUNCTION [ANY, TUPLE, EV_HELP_CONTEXT]
			-- Agent that evaluates to help context sent to help engine when help is requested
			-- (from EV_HELP_CONTEXTABLE)
		require -- from EV_HELP_CONTEXTABLE
			not_destroyed: not is_destroyed
		ensure -- from EV_HELP_CONTEXTABLE
			bridge_ok: Result = implementation.help_context

	i_th (i: INTEGER): EV_WIDGET
			-- Item at i-th position.
			-- (from EV_DYNAMIC_LIST)
		require -- from TABLE
			valid_key: valid_index (k)
		ensure then -- from EV_DYNAMIC_LIST
			bridge_ok: Result.is_equal (implementation.i_th (i))

	frozen id_object (an_id: INTEGER): IDENTIFIED
			-- Object associated with an_id (void if no such object)
			-- (from IDENTIFIED)
		ensure -- from IDENTIFIED
			consistent: Result = void or else Result.object_id = an_id

	index: INTEGER
			-- Current position.
			-- (from EV_DYNAMIC_LIST)
		ensure then -- from EV_DYNAMIC_LIST
			bridge_ok: Result = implementation.index

	index_of (v: like item; i: INTEGER): INTEGER
			-- Index of ith occurence of v.
			-- (from EV_DYNAMIC_LIST)
		require -- from LINEAR
			positive_occurrences: i > 0
		ensure -- from LINEAR
			non_negative_result: Result >= 0
		ensure then -- from EV_DYNAMIC_LIST
			bridge_ok: Result = implementation.index_of (v, i)

	is_parent_recursive (a_widget: EV_WIDGET): BOOLEAN
			-- Is a_widget parent, or recursively, parent of parent.
			-- (from EV_WIDGET)
		require -- from EV_DYNAMIC_LIST
			a_list_not_void: a_list /= void
		require -- from EV_WIDGET
			not_destroyed: not is_destroyed

	item: EV_WIDGET
			-- Item at current position.
			-- (from EV_DYNAMIC_LIST)
		require -- from TRAVERSABLE
			not_off: not off
		require -- from ACTIVE
			readable: readable
		require -- from EV_CONTAINER
			not_destroyed: not is_destroyed
			readable: readable
		ensure -- from EV_CONTAINER
			bridge_ok: Result = implementation.item
		ensure then -- from EV_DYNAMIC_LIST
			not_void: Result /= void
			bridge_ok: Result.is_equal (implementation.item)

	last: like item
			-- Item at last position
			-- (from CHAIN)
		require -- from CHAIN
			not_empty: not is_empty

	frozen object_id: INTEGER
			-- Unique for current object in any given session
			-- (from IDENTIFIED)
		ensure -- from IDENTIFIED
			valid_id: id_object (Result) = Current

	sequential_occurrences (v: EV_WIDGET): INTEGER
			-- Number of times v appears.
			-- (Reference or object equality,
			-- based on object_comparison.)
			-- (from LINEAR)
		ensure -- from BAG
			non_negative_occurrences: Result >= 0

	parent: EV_CONTAINER
			-- Contains Current.
			-- (from EV_WIDGET)
		require -- from EV_CONTAINABLE
			not_destroyed: not is_destroyed
		ensure then -- from EV_WIDGET
			bridge_ok: Result = implementation.parent

	pebble: ANY
			-- Data to be transported by pick and drop mechanism.
			-- (from EV_PICK_AND_DROPABLE)
		ensure then -- from EV_PICK_AND_DROPABLE
			bridge_ok: Result = implementation.pebble

	pebble_function: FUNCTION [ANY, TUPLE, ANY]
			-- Returns data to be transported by pick and drop mechanism.
			-- (from EV_PICK_AND_DROPABLE)
		ensure then -- from EV_PICK_AND_DROPABLE
			bridge_ok: Result = implementation.pebble_function

	pebble_positioning_enabled: BOOLEAN
			-- If True then pick and drop start coordinates are
			-- pebble_x_position, pebble_y_position.
			-- If False then pick and drop start coordinates are
			-- the pointer coordinates.
			-- (from EV_PICK_AND_DROPABLE)
		require -- from EV_PICK_AND_DROPABLE
			not_destroyed: not is_destroyed
		ensure then -- from EV_PICK_AND_DROPABLE
			bridge_ok: Result = implementation.pebble_positioning_enabled

	pebble_x_position: INTEGER
			-- Initial x position for pick and drop relative to Current.
			-- (from EV_PICK_AND_DROPABLE)
		ensure then -- from EV_PICK_AND_DROPABLE
			bridge_ok: Result = implementation.pebble_x_position

	pebble_y_position: INTEGER
			-- Initial y position for pick and drop relative to Current.
			-- (from EV_PICK_AND_DROPABLE)
		ensure then -- from EV_PICK_AND_DROPABLE
			bridge_ok: Result = implementation.pebble_y_position

	pointer_position: EV_COORDINATE
			-- Position of the screen pointer relative to Current.
			-- (from EV_WIDGET)
		require -- from EV_WIDGET
			not_destroyed: not is_destroyed
			is_show_requested: is_show_requested

	pointer_style: EV_CURSOR
			-- Cursor displayed when pointer is over this widget.
			-- (from EV_WIDGET)
		require -- from EV_WIDGET
			not_destroyed: not is_destroyed

	target_name: STRING
			-- Optional textual name describing Current pick and drop hole.
			-- (from EV_ABSTRACT_PICK_AND_DROPABLE)

	infix "@" (i: INTEGER): like item
			-- Item at i-th position
			-- Was declared in CHAIN as synonym of i_th.
			-- (from CHAIN)
		require -- from TABLE
			valid_key: valid_index (k)
	
feature -- Measurement

	client_height: INTEGER
			-- Height of the area available to children in pixels.
			-- (from EV_CONTAINER)
		require -- from EV_CONTAINER
			not_destroyed: not is_destroyed
		ensure -- from EV_CONTAINER
			bridge_ok: Result = implementation.client_height

	client_width: INTEGER
			-- Width of the area available to children in pixels.
			-- (from EV_CONTAINER)
		require -- from EV_CONTAINER
			not_destroyed: not is_destroyed
		ensure -- from EV_CONTAINER
			bridge_ok: Result = implementation.client_width

	count: INTEGER
			-- Number of items.
			-- (from EV_DYNAMIC_LIST)
		require -- from  FINITE
			True
		require -- from  SET
			True
		require -- from EV_CONTAINER
			not_destroyed: not is_destroyed
		ensure then -- from EV_DYNAMIC_LIST
			bridge_ok: Result = implementation.count

	height: INTEGER
			-- Vertical size in pixels.
			-- Same as minimum_height when not displayed.
			-- (from EV_POSITIONED)
		require -- from EV_POSITIONED
			not_destroyed: not is_destroyed
		ensure -- from EV_POSITIONED
			bridge_ok: Result = implementation.height

	index_set: INTEGER_INTERVAL
			-- Range of acceptable indexes
			-- (from CHAIN)
		ensure -- from INDEXABLE
			not_void: Result /= void
		ensure then -- from CHAIN
			count_definition: Result.count = count

	minimum_height: INTEGER
			-- Lower bound on height in pixels.
			-- (from EV_POSITIONED)
		require -- from EV_POSITIONED
			not_destroyed: not is_destroyed
		ensure -- from EV_POSITIONED
			bridge_ok: Result = implementation.minimum_height
			positive_or_zero: Result >= 0

	minimum_width: INTEGER
			-- Lower bound on width in pixels.
			-- (from EV_POSITIONED)
		require -- from EV_POSITIONED
			not_destroyed: not is_destroyed
		ensure -- from EV_POSITIONED
			bridge_ok: Result = implementation.minimum_width
			positive_or_zero: Result >= 0

	occurrences (v: like item): INTEGER
			-- Number of times v appears.
			-- (Reference or object equality,
			-- based on object_comparison.)
			-- (from CHAIN)
		ensure -- from BAG
			non_negative_occurrences: Result >= 0

	occurrences (v: like item): INTEGER
			-- Number of times v appears.
			-- (Reference or object equality,
			-- based on object_comparison.)
			-- (from CHAIN)
		ensure -- from BAG
			non_negative_occurrences: Result >= 0

	screen_x: INTEGER
			-- Horizontal offset relative to left of screen in pixels.
			-- (from EV_WIDGET)
		require -- from EV_WIDGET
			not_destroyed: not is_destroyed
		ensure -- from EV_WIDGET
			bridge_ok: Result = implementation.screen_x

	screen_y: INTEGER
			-- Vertical offset relative to top of screen in pixels.
			-- (from EV_WIDGET)
		require -- from EV_WIDGET
			not_destroyed: not is_destroyed
		ensure -- from EV_WIDGET
			bridge_ok: Result = implementation.screen_y

	width: INTEGER
			-- Horizontal size in pixels.
			-- Same as minimum_width when not displayed.
			-- (from EV_POSITIONED)
		require -- from EV_POSITIONED
			not_destroyed: not is_destroyed
		ensure -- from EV_POSITIONED
			bridge_ok: Result = implementation.width

	x_position: INTEGER
			-- Horizontal offset relative to parent x_position in pixels.
			-- (from EV_POSITIONED)
		require -- from EV_POSITIONED
			not_destroyed: not is_destroyed
		ensure -- from EV_POSITIONED
			bridge_ok: Result = implementation.x_position

	y_position: INTEGER
			-- Vertical offset relative to parent y_position in pixels.
			-- (from EV_POSITIONED)
		require -- from EV_POSITIONED
			not_destroyed: not is_destroyed
		ensure -- from EV_POSITIONED
			bridge_ok: Result = implementation.y_position
	
feature -- Comparison

	is_equal (other: like Current): BOOLEAN
			-- Does other contain the same elements?
			-- (from LIST)
		require -- from ANY
			other_not_void: other /= void
		ensure -- from ANY
			symmetric: Result implies other.is_equal (Current)
			consistent: standard_is_equal (other) implies Result
		ensure then -- from LIST
			indices_unchanged: index = old index and other.index = old other.index
			true_implies_same_size: Result implies count = other.count
	
feature -- Status report

	after: BOOLEAN
			-- Is there no valid cursor position to the right of cursor?
			-- (from LIST)

	before: BOOLEAN
			-- Is there no valid cursor position to the left of cursor?
			-- (from LIST)

	border_width: INTEGER
			-- Width of border around container in pixels.
		require
			not_destroyed: not is_destroyed
		ensure
			bridge_ok: Result = implementation.border_width
			positive: Result >= 0

	exhausted: BOOLEAN
			-- Has structure been completely explored?
			-- (from LINEAR)
		ensure -- from LINEAR
			exhausted_when_off: off implies Result

	Extendible: BOOLEAN is True
			-- May new items be added? (Answer: yes.)
			-- (from DYNAMIC_CHAIN)

	Full: BOOLEAN is False
			-- Is structured filled to capacity? (Answer: no.)
			-- (from EV_DYNAMIC_LIST)

	has_capture: BOOLEAN
			-- Does widget have capture?
			-- (from EV_WIDGET)
		require -- from EV_WIDGET
			not_destroyed: not is_destroyed
		ensure -- from EV_WIDGET
			bridge_ok: Result = implementation.has_capture

	has_focus: BOOLEAN
			-- Does widget have the keyboard focus?
			-- (from EV_WIDGET)
		require -- from EV_WIDGET
			not_destroyed: not is_destroyed
		ensure -- from EV_WIDGET
			bridge_ok: Result = implementation.has_focus

	is_displayed: BOOLEAN
			-- Is Current visible on the screen?
			-- True when show requested and parent displayed.
			-- (from EV_WIDGET)
		require -- from EV_WIDGET
			not_destroyed: not is_destroyed
		ensure -- from EV_WIDGET
			bridge_ok: Result = implementation.is_displayed

	is_empty: BOOLEAN
			-- Is structure empty?
			-- (from FINITE)

	is_homogeneous: BOOLEAN
			-- Are all items forced to have same dimensions.
		require
			not_destroyed: not is_destroyed
		ensure
			bridge_ok: Result = implementation.is_homogeneous

	is_inserted (v: EV_WIDGET): BOOLEAN
			-- Has v been inserted by the most recent insertion?
			-- (By default, the value returned is equivalent to calling
			-- `has (v)'. However, descendants might be able to provide more
			-- efficient implementations.)
			-- (from COLLECTION)

	is_item_expanded (an_item: EV_WIDGET): BOOLEAN
			-- Is an_item expanded to occupy available spare space?
		require
			not_destroyed: not is_destroyed
			has_an_item: has (an_item)
		ensure
			bridge_ok: Result = implementation.is_item_expanded (an_item)

	is_sensitive: BOOLEAN
			-- Is object sensitive to user input.
			-- (from EV_SENSITIVE)
		require -- from EV_SENSITIVE
			not_destroyed: not is_destroyed
		ensure -- from EV_SENSITIVE
			bridge_ok: Result = implementation.user_is_sensitive

	is_show_requested: BOOLEAN
			-- Will Current be displayed when its parent is?
			-- See also is_displayed.
			-- (from EV_WIDGET)
		require -- from EV_WIDGET
			not_destroyed: not is_destroyed
		ensure -- from EV_WIDGET
			bridge_ok: Result = implementation.is_show_requested

	isfirst: BOOLEAN
			-- Is cursor at first position?
			-- (from CHAIN)
		ensure -- from CHAIN
			valid_position: Result implies not is_empty

	islast: BOOLEAN
			-- Is cursor at last position?
			-- (from CHAIN)
		ensure -- from CHAIN
			valid_position: Result implies not is_empty

	mode_is_drag_and_drop: BOOLEAN
			-- Is the user interface mode drag and drop?
			-- (from EV_PICK_AND_DROPABLE)
		require -- from EV_PICK_AND_DROPABLE
			not_destroyed: not is_destroyed
		ensure then -- from EV_PICK_AND_DROPABLE
			bridge_ok: Result = implementation.mode_is_drag_and_drop

	mode_is_pick_and_drop: BOOLEAN
			-- Is the user interface mode pick and drop?
			-- (from EV_PICK_AND_DROPABLE)
		require -- from EV_PICK_AND_DROPABLE
			not_destroyed: not is_destroyed
		ensure then -- from EV_PICK_AND_DROPABLE
			bridge_ok: Result = implementation.mode_is_pick_and_drop

	mode_is_target_menu: BOOLEAN
			-- Is the user interface mode a pop-up menu of targets?
			-- (from EV_PICK_AND_DROPABLE)
		require -- from EV_PICK_AND_DROPABLE
			not_destroyed: not is_destroyed
		ensure then -- from EV_PICK_AND_DROPABLE
			bridge_ok: Result = implementation.mode_is_target_menu

	off: BOOLEAN
			-- Is there no current item?
			-- (from CHAIN)

	padding: INTEGER
			-- Space between children in pixels.
		require
			not_destroyed: not is_destroyed
		ensure
			bridge_ok: Result = implementation.padding
			positive: Result >= 0

	prunable: BOOLEAN
			-- May items be removed? (Answer: yes.)
			-- (from DYNAMIC_CHAIN)

	readable: BOOLEAN
			-- Is there a current item that may be read?
			-- (from SEQUENCE)
		require -- from  ACTIVE
			True
		require -- from EV_CONTAINER
			not_destroyed: not is_destroyed

	valid_cursor (p: CURSOR): BOOLEAN
			-- Can the cursor be moved to position p?
			-- This is True if p conforms to EV_DYNAMIC_LIST_CURSOR and
			-- if it points to an item, Current must have it.
			-- (from EV_DYNAMIC_LIST)
		ensure then -- from EV_DYNAMIC_LIST
			bridge_ok: Result = implementation.valid_cursor (p)

	valid_cursor_index (i: INTEGER): BOOLEAN
			-- Is i correctly bounded for cursor movement?
			-- (from CHAIN)
		ensure -- from CHAIN
			valid_cursor_index_definition: Result = ((i >= 0) and (i <= count + 1))

	valid_index (i: INTEGER): BOOLEAN
			-- Is i within allowable bounds?
			-- (from CHAIN)
		ensure then -- from INDEXABLE
			only_if_in_index_set: Result implies ((i >= index_set.lower) and (i <= index_set.upper))
		ensure then -- from CHAIN
			valid_index_definition: Result = ((i >= 1) and (i <= count))

	writable: BOOLEAN
			-- Is there a current item that may be modified?
			-- (from SEQUENCE)
		require -- from  ACTIVE
			True
		require -- from EV_CONTAINER
			not_destroyed: not is_destroyed
	
feature -- Status setting

	center_pointer
			-- Position screen pointer over center of Current.
			-- (from EV_WIDGET)
		require -- from EV_WIDGET
			not_destroyed: not is_destroyed

	disable_capture
			-- Disable grab of all user input events.
			-- (from EV_WIDGET)
		require -- from EV_WIDGET
			not_destroyed: not is_destroyed
		ensure -- from EV_WIDGET
			not_has_capture: not has_capture

	disable_homogeneous
			-- Allow items to have different dimensions.
		require
			not_destroyed: not is_destroyed
		ensure
			not_is_homogeneous: not is_homogeneous

	disable_item_expand (an_item: EV_WIDGET)
			-- Do not expand an_item to occupy available spare space.
		require
			not_destroyed: not is_destroyed
			has_an_item: has (an_item)
		ensure
			not_an_item_expanded: not is_item_expanded (an_item)

	disable_pebble_positioning
			-- Assign False to pebble_positioning_enabled.
			-- The pick and drop will start at the pointer position.
			-- (from EV_PICK_AND_DROPABLE)
		require -- from EV_PICK_AND_DROPABLE
			not_destroyed: not is_destroyed
		ensure -- from EV_PICK_AND_DROPABLE
			pebble_positioning_updated: not pebble_positioning_enabled

	disable_sensitive
			-- Make object non-sensitive to user input.
			-- (from EV_SENSITIVE)
		require -- from EV_SENSITIVE
			not_destroyed: not is_destroyed
		ensure -- from EV_SENSITIVE
			is_unsensitive: not is_sensitive

	enable_capture
			-- Grab all user input events (mouse and keyboard).
			-- disable_capture must be called to resume normal input handling.
			-- (from EV_WIDGET)
		require -- from EV_WIDGET
			not_destroyed: not is_destroyed
			is_displayed: is_displayed
		ensure -- from EV_WIDGET
			has_capture: has_capture

	enable_homogeneous
			-- Force all items to have same dimensions.
		require
			not_destroyed: not is_destroyed
		ensure
			is_homogeneous: is_homogeneous

	enable_item_expand (an_item: EV_WIDGET)
			-- Expand an_item to occupy available spare space.
		require
			not_destroyed: not is_destroyed
			has_an_item: has (an_item)
		ensure
			an_item_expanded: is_item_expanded (an_item)

	enable_pebble_positioning
			-- Assign True to pebble_positioning_enabled.
			-- Use pebble_x_position and pebble_y_position as the initial coordinates
			-- for the pick and drop in pixels relative to Current.
			-- (from EV_PICK_AND_DROPABLE)
		require -- from EV_PICK_AND_DROPABLE
			not_destroyed: not is_destroyed
		ensure -- from EV_PICK_AND_DROPABLE
			pebble_positioning_updated: pebble_positioning_enabled

	enable_sensitive
			-- Make object sensitive to user input.
			-- (from EV_SENSITIVE)
		require -- from EV_SENSITIVE
			not_destroyed: not is_destroyed
		ensure -- from EV_SENSITIVE
			is_sensitive: (parent = void or parent_is_sensitive) implies is_sensitive

	hide
			-- Request that Current not be displayed even when its parent is.
			-- Make is_show_requested False.
			-- (from EV_WIDGET)
		require -- from EV_WIDGET
			not_destroyed: not is_destroyed
		ensure -- from EV_WIDGET
			not_is_show_requested: not is_show_requested

	merge_radio_button_groups (other: EV_CONTAINER)
			-- Merge Current radio button group with that of other.
			-- (from EV_CONTAINER)
		require -- from EV_CONTAINER
			not_destroyed: not is_destroyed
			other_not_void: other /= void

	remove_pebble
			-- Make pebble Void and pebble_function `Void,
			-- Removing transport.
			-- (from EV_PICK_AND_DROPABLE)
		ensure -- from EV_ABSTRACT_PICK_AND_DROPABLE
			pebble_removed: pebble = void and pebble_function = void

	set_accept_cursor (a_cursor: EV_CURSOR)
			-- Set a_cursor to be displayed when the screen pointer is over a
			-- target that accepts pebble during pick and drop.
			-- (from EV_PICK_AND_DROPABLE)
		ensure -- from EV_ABSTRACT_PICK_AND_DROPABLE
			accept_cursor_assigned: accept_cursor.is_equal (a_cursor)

	set_actual_drop_target_agent (an_agent: like actual_drop_target_agent)
			-- Assign an_agent to actual_drop_target_agent.
			-- (from EV_WIDGET)
		require -- from EV_WIDGET
			not_destroyed: not is_destroyed
			an_agent_not_void: an_agent /= void
		ensure -- from EV_WIDGET
			assigned: actual_drop_target_agent = an_agent

	set_border_width (value: INTEGER)
			-- Assign value to border_width.
		require
			not_destroyed: not is_destroyed
			positive_value: value >= 0
		ensure
			border_width_assigned: border_width = value

	set_default_colors
			-- Set foreground and background color to their default values.
			-- (from EV_COLORIZABLE)
		require -- from EV_COLORIZABLE
			not_destroyed: not is_destroyed

	set_deny_cursor (a_cursor: EV_CURSOR)
			-- Set a_cursor to be displayed when the screen pointer is not
			-- over a valid target.
			-- (from EV_PICK_AND_DROPABLE)
		ensure -- from EV_ABSTRACT_PICK_AND_DROPABLE
			deny_cursor_assigned: deny_cursor.is_equal (a_cursor)

	set_drag_and_drop_mode
			-- Set user interface mode to drag and drop.
			-- (from EV_PICK_AND_DROPABLE)
		require -- from EV_PICK_AND_DROPABLE
			not_destroyed: not is_destroyed
		ensure -- from EV_PICK_AND_DROPABLE
			drag_and_drop_set: mode_is_drag_and_drop

	set_focus
			-- Grab keyboard focus.
			-- (from EV_WIDGET)
		require -- from EV_WIDGET
			not_destroyed: not is_destroyed
			is_displayed: is_displayed
			is_sensitive: is_sensitive
		ensure -- from EV_WIDGET
			has_focus: has_focus

	set_padding (value: INTEGER)
			-- Assign value to padding.
		require
			not_destroyed: not is_destroyed
			positive_value: value >= 0
		ensure
			padding_assigned: padding = value

	set_pebble (a_pebble: like pebble)
			-- Assign a_pebble to pebble.
			-- Overrides set_pebble_function.
			-- (from EV_PICK_AND_DROPABLE)
		require -- from EV_ABSTRACT_PICK_AND_DROPABLE
			a_pebble_not_void: a_pebble /= void
		ensure -- from EV_ABSTRACT_PICK_AND_DROPABLE
			pebble_assigned: pebble = a_pebble

	set_pebble_function (a_function: FUNCTION [ANY, TUPLE, ANY])
			-- Set a_function to compute pebble.
			-- It will be called once each time a pick occurs, the result
			-- will be assigned to pebble for the duration of transport.
			-- When a pick occurs, the pick position in widget coordinates,
			-- <<x, y>> in pixels, is passed.
			-- To handle this data use a_function of type
			-- FUNCTION [ANY, TUPLE [INTEGER, INTEGER], ANY] and return the
			-- pebble as a function of x and y.
			-- Overrides set_pebble.
			-- (from EV_PICK_AND_DROPABLE)
		require -- from EV_ABSTRACT_PICK_AND_DROPABLE
			a_function_not_void: a_function /= void
			a_function_takes_two_integer_open_operands: a_function.valid_operands ([1, 1])
		ensure -- from EV_ABSTRACT_PICK_AND_DROPABLE
			pebble_function_assigned: pebble_function = a_function

	set_pebble_position (a_x, a_y: INTEGER)
			-- Set the initial position for pick and drop
			-- Coordinates are in pixels and are relative to position of Current.
			-- Pebble_positioning_enabled must be True for the position to be used,
			-- use enable_pebble_positioning.
			-- (from EV_PICK_AND_DROPABLE)
		require -- from EV_PICK_AND_DROPABLE
			not_destroyed: not is_destroyed
		ensure -- from EV_PICK_AND_DROPABLE
			pebble_position_assigned: pebble_x_position = a_x and pebble_y_position = a_y

	set_pick_and_drop_mode
			-- Set user interface mode to pick and drop.
			-- (from EV_PICK_AND_DROPABLE)
		require -- from EV_PICK_AND_DROPABLE
			not_destroyed: not is_destroyed
		ensure -- from EV_PICK_AND_DROPABLE
			pick_and_drop_set: mode_is_pick_and_drop

	set_target_menu_mode
			-- Set user interface mode to pop-up menu of targets.
			-- (from EV_PICK_AND_DROPABLE)
		require -- from EV_PICK_AND_DROPABLE
			not_destroyed: not is_destroyed
		ensure -- from EV_PICK_AND_DROPABLE
			target_menu_mode_set: mode_is_target_menu

	set_target_name (a_name: STRING)
			-- Assign a_name to target_name.
			-- (from EV_ABSTRACT_PICK_AND_DROPABLE)
		require -- from EV_ABSTRACT_PICK_AND_DROPABLE
			a_name_not_void: a_name /= void
		ensure -- from EV_ABSTRACT_PICK_AND_DROPABLE
			target_name_assigned: a_name /= target_name and a_name.is_equal (target_name)

	show
			-- Request that Current be displayed when its parent is.
			-- True by default.
			-- Make is_show_requested True.
			-- (from EV_WIDGET)
		require -- from EV_WIDGET
			not_destroyed: not is_destroyed
		ensure -- from EV_WIDGET
			is_show_requested: is_show_requested
	
feature -- Cursor movement

	back
			-- Move to previous position.
			-- (from EV_DYNAMIC_LIST)
		require -- from BILINEAR
			not_before: not before

	finish
			-- Move cursor to last position.
			-- (No effect if empty)
			-- (from CHAIN)
		ensure then -- from CHAIN
			at_last: not is_empty implies islast

	forth
			-- Move cursor to next position.
			-- (from EV_DYNAMIC_LIST)
		require -- from LINEAR
			not_after: not after
		ensure then -- from LIST
			moved_forth: index = old index + 1

	go_i_th (i: INTEGER)
			-- Move cursor to i-th position.
			-- (from EV_DYNAMIC_LIST)
		require -- from CHAIN
			valid_cursor_index: valid_cursor_index (i)
		ensure -- from CHAIN
			position_expected: index = i

	go_to (p: CURSOR)
			-- Move cursor to position p.
			-- (from EV_DYNAMIC_LIST)
		require -- from CURSOR_STRUCTURE
			cursor_position_valid: valid_cursor (p)

	move (i: INTEGER)
			-- Move cursor i positions.
			-- (from EV_DYNAMIC_LIST)
		ensure -- from CHAIN
			too_far_right: (old index + i > count) implies exhausted
			too_far_left: (old index + i < 1) implies exhausted
			expected_index: (not exhausted) implies (index = old index + i)

	search (v: like item)
			-- Move to first position (at or after current
			-- position) where item and v are equal.
			-- If structure does not include v ensure that
			-- exhausted will be true.
			-- (Reference or object equality,
			-- based on object_comparison.)
			-- (from BILINEAR)
		ensure -- from LINEAR
			object_found: (not exhausted and object_comparison) implies equal (v, item)
			item_found: (not exhausted and not object_comparison) implies v = item

	start
			-- Move cursor to first position.
			-- (from EV_DYNAMIC_LIST)
		ensure then -- from CHAIN
			at_first: not is_empty implies isfirst
		ensure then -- from EV_DYNAMIC_LIST
			empty_implies_after: is_empty implies after
	
feature -- Element change

	append (s: SEQUENCE [EV_WIDGET])
			-- Append a copy of s.
			-- (from SEQUENCE)
		require -- from SEQUENCE
			argument_not_void: s /= void
		ensure -- from SEQUENCE
			new_count: count >= old count

	extend (v: like item)
			-- Add v to end. Do not move cursor.
			-- (from EV_DYNAMIC_LIST)
		require -- from EV_CONTAINER
			not_destroyed: not is_destroyed
			extendible: extendible
			v_not_void: v /= void
			v_parent_void: v.parent = void
			v_not_current: v /= Current
			v_not_parent_of_current: not is_parent_recursive (v)
			v_not_window: not v.conforms_to (create {EV_WINDOW})
		require -- from EV_DYNAMIC_LIST
			not_destroyed: not is_destroyed
			extendible: extendible
			v_not_void: v /= void
			v_parent_void: v.parent = void
			v_not_current: not same (v)
			v_not_parent_of_current: not is_parent_recursive (v)
		ensure -- from EV_CONTAINER
			has_v: has (v)
		ensure -- from EV_DYNAMIC_LIST
			parent_is_current: v.parent = Current
			v_is_last: v = last
			count_increased: count = old count + 1
			cursor_not_moved: (index = old index) or (after and old after)

	fill (other: CONTAINER [EV_WIDGET])
			-- Fill with as many items of other as possible.
			-- The representations of other and current structure
			-- need not be the same.
			-- (from COLLECTION)
		require -- from COLLECTION
			other_not_void: other /= void
			extendible

	force (v: like item)
			-- Add v to end.
			-- (from SEQUENCE)
		require -- from SEQUENCE
			extendible: extendible
		ensure then -- from SEQUENCE
			new_count: count = old count + 1
			item_inserted: has (v)

	merge_left (other: like Current)
			-- Merge other into current structure before cursor
			-- position. Do not move cursor. Empty other.
			-- (from EV_DYNAMIC_LIST)
		require -- from DYNAMIC_CHAIN
			extendible: extendible
			not_before: not before
			other_exists: other /= void
		ensure -- from DYNAMIC_CHAIN
			new_count: count = old count + old other.count
			new_index: index = old index + old other.count
			other_is_empty: other.is_empty
		ensure then -- from DYNAMIC_LIST
			other_empty: other.is_empty

	merge_right (other: like Current)
			-- Merge other into current structure after cursor
			-- position. Do not move cursor. Empty other.
			-- (from EV_DYNAMIC_LIST)
		require -- from DYNAMIC_CHAIN
			extendible: extendible
			not_after: not after
			other_exists: other /= void
		ensure -- from DYNAMIC_CHAIN
			new_count: count = old count + old other.count
			same_index: index = old index
			other_is_empty: other.is_empty
		ensure then -- from DYNAMIC_LIST
			other_empty: other.is_empty

	put (v: like item)
			-- Replace current item by v.
			-- (Synonym for replace)
			-- (from CHAIN)
		require -- from COLLECTION
			extendible: extendible
		require -- from EV_CONTAINER
			not_destroyed: not is_destroyed
			writable: writable
			v_not_void: v /= void
			v_parent_void: v.parent = void
			v_not_current: v /= Current
			v_not_parent_of_current: not is_parent_recursive (v)
			v_not_window: not v.conforms_to (create {EV_WINDOW})
		ensure -- from COLLECTION
			item_inserted: is_inserted (v)
		ensure then -- from SET
			in_set_already: old has (v) implies (count = old count)
			added_to_set: not old has (v) implies (count = old count + 1)
		ensure then -- from CHAIN
			same_count: count = old count
		ensure -- from EV_CONTAINER
			has_v: has (v)

	put (v: like item)
			-- Replace current item by v.
			-- (Synonym for replace)
			-- (from CHAIN)
		require -- from COLLECTION
			extendible: extendible
		require -- from EV_CONTAINER
			not_destroyed: not is_destroyed
			writable: writable
			v_not_void: v /= void
			v_parent_void: v.parent = void
			v_not_current: v /= Current
			v_not_parent_of_current: not is_parent_recursive (v)
			v_not_window: not v.conforms_to (create {EV_WINDOW})
		ensure -- from COLLECTION
			item_inserted: is_inserted (v)
		ensure then -- from SET
			in_set_already: old has (v) implies (count = old count)
			added_to_set: not old has (v) implies (count = old count + 1)
		ensure then -- from CHAIN
			same_count: count = old count
		ensure -- from EV_CONTAINER
			has_v: has (v)

	put_front (v: like item)
			-- Add v at beginning. Do not move cursor.
			-- (from EV_DYNAMIC_LIST)
		require -- from EV_DYNAMIC_LIST
			not_destroyed: not is_destroyed
			extendible: extendible
			v_not_void: v /= void
			v_parent_void: v.parent = void
			v_not_current: not same (v)
			v_not_parent_of_current: not is_parent_recursive (v)
		ensure -- from EV_DYNAMIC_LIST
			parent_is_current: v.parent = Current
			v_is_first: v = first
			count_increased: count = old count + 1
			cursor_not_moved: (index = old index + 1) or (before and old before)

	put_i_th (v: like item; i: INTEGER)
			-- Replace item at i-th position by v.
			-- (from EV_DYNAMIC_LIST)
		require -- from EV_DYNAMIC_LIST
			not_destroyed: not is_destroyed
			valid_index: i > 0 and i <= count
			v_not_void: v /= void
			v_parent_void: v.parent = void
			v_not_current: not same (v)
			v_not_parent_of_current: not is_parent_recursive (v)
		ensure -- from EV_DYNAMIC_LIST
			parent_is_current: v.parent = Current
			item_replaced: v = i_th (i)
			not_has_old_item: not has (old i_th (i))
			old_item_parent_void: (old i_th (i)).parent = void
			count_same: count = old count
			cursor_not_moved: index = old index

	put_left (v: like item)
			-- Add v to the left of cursor position. Do not move cursor.
			-- (from EV_DYNAMIC_LIST)
		require -- from EV_DYNAMIC_LIST
			not_destroyed: not is_destroyed
			extendible: extendible
			not_before: not before
			v_not_void: v /= void
			v_parent_void: v.parent = void
			v_not_current: not same (v)
			v_not_parent_of_current: not is_parent_recursive (v)
		ensure -- from EV_DYNAMIC_LIST
			parent_is_current: v.parent = Current
			v_at_index_plus_one: v = i_th (index - 1)
			count_increased: count = old count + 1
			cursor_not_moved: index = old index + 1

	put_right (v: like item)
			-- Add v to right of cursor position. Do not move cursor.
			-- (from EV_DYNAMIC_LIST)
		require -- from EV_DYNAMIC_LIST
			not_destroyed: not is_destroyed
			extendible: extendible
			not_after: not after
			v_not_void: v /= void
			v_parent_void: v.parent = void
			v_not_current: not same (v)
			v_not_parent_of_current: not is_parent_recursive (v)
		ensure -- from EV_DYNAMIC_LIST
			parent_is_current: v.parent = Current
			v_at_index_plus_one: v = i_th (index + 1)
			count_increased: count = old count + 1
			cursor_not_moved: index = old index

	remove_help_context
			-- Remove key press action associated with EV_APPLICATION.help_key.
			-- (from EV_HELP_CONTEXTABLE)
		require -- from EV_HELP_CONTEXTABLE
			not_destroyed: not is_destroyed
			help_context_not_void: help_context /= void
		ensure -- from EV_HELP_CONTEXTABLE
			no_help_context: help_context = void

	replace (v: like item)
			-- Replace current item by v.
			-- (from EV_DYNAMIC_LIST)
		require -- from EV_CONTAINER
			not_destroyed: not is_destroyed
			writable: writable
			v_not_void: v /= void
			v_parent_void: v.parent = void
			v_not_current: v /= Current
			v_not_parent_of_current: not is_parent_recursive (v)
			v_not_window: not v.conforms_to (create {EV_WINDOW})
		require -- from EV_DYNAMIC_LIST
			not_destroyed: not is_destroyed
			writable: writable
			v_not_void: v /= void
			v_parent_void: v.parent = void
			v_not_current: not same (v)
			v_not_parent_of_current: not is_parent_recursive (v)
		ensure -- from EV_CONTAINER
			has_v: has (v)
		ensure -- from EV_DYNAMIC_LIST
			parent_is_current: v.parent = Current
			item_replaced: v = item
			not_has_old_item: not has (old item)
			old_item_parent_void: (old item).parent = void
			count_same: count = old count
			cursor_not_moved: index = old index

	set_background_color (a_color: like background_color)
			-- Assign a_color to foreground_color.
			-- (from EV_COLORIZABLE)
		require -- from EV_COLORIZABLE
			not_destroyed: not is_destroyed
			a_color_not_void: a_color /= void
		ensure -- from EV_COLORIZABLE
			background_color_assigned: background_color.is_equal (a_color)

	set_data (some_data: like data)
			-- Assign some_data to data.
			-- (from EV_ANY)
		require -- from EV_ANY
			not_destroyed: not is_destroyed
		ensure -- from EV_ANY
			data_assigned: data = some_data

	set_foreground_color (a_color: like foreground_color)
			-- Assign a_color to foreground_color.
			-- (from EV_COLORIZABLE)
		require -- from EV_COLORIZABLE
			not_destroyed: not is_destroyed
			a_color_not_void: a_color /= void
		ensure -- from EV_COLORIZABLE
			foreground_color_assigned: foreground_color.is_equal (a_color)

	set_help_context (an_help_context: like help_context)
			-- Assign an_help_context to help_context.
			-- (from EV_HELP_CONTEXTABLE)
		require -- from EV_HELP_CONTEXTABLE
			not_destroyed: not is_destroyed
			an_help_context_not_void: an_help_context /= void
		ensure -- from EV_HELP_CONTEXTABLE
			help_context_assigned: help_context.is_equal (an_help_context)

	set_minimum_height (a_minimum_height: INTEGER)
			-- Set a_minimum_height in pixels to minimum_height.
			-- If height is less than a_minimim_height, resize.
			-- This setting takes effect next time application is idle.
			-- From now, minimum_height is fixed and will not be changed
			-- dynamically by the application anymore.
			-- (from EV_WIDGET)
		require -- from EV_WIDGET
			not_destroyed: not is_destroyed
			a_minimum_height_positive: a_minimum_height > 0
		ensure -- from EV_WIDGET
			minimum_height_assigned: minimum_height = a_minimum_height

	set_minimum_size (a_minimum_width, a_minimum_height: INTEGER)
			-- Assign a_minimum_height to minimum_height
			-- and a_minimum_width to minimum_width in pixels.
			-- If width or height is less than minimum size, resize.
			-- This setting takes effect next time application is idle.
			-- From now, minimum size is fixed and will not be changed
			-- dynamically by the application anymore.
			-- (from EV_WIDGET)
		require -- from EV_WIDGET
			not_destroyed: not is_destroyed
			a_minimum_width_positive: a_minimum_width > 0
			a_minimum_height_positive: a_minimum_height > 0
		ensure -- from EV_WIDGET
			minimum_width_assigned: minimum_width = a_minimum_width
			minimum_height_assigned: minimum_height = a_minimum_height

	set_minimum_width (a_minimum_width: INTEGER)
			-- Assign a_minimum_width in pixels to minimum_width.
			-- If width is less than a_minimim_width, resize.
			-- This setting takes effect next time application is idle.
			-- From now, minimum_width is fixed and will not be changed
			-- dynamically by the application anymore.
			-- (from EV_WIDGET)
		require -- from EV_WIDGET
			not_destroyed: not is_destroyed
			a_minimum_width_positive: a_minimum_width > 0
		ensure -- from EV_WIDGET
			minimum_width_assigned: minimum_width = a_minimum_width

	set_pointer_style (a_cursor: like pointer_style)
			-- Assign a_cursor to pointer_style.
			-- (from EV_WIDGET)
		require -- from EV_WIDGET
			not_destroyed: not is_destroyed
			a_cursor_not_void: a_cursor /= void
		ensure -- from EV_WIDGET
			pointer_style_assigned: pointer_style.is_equal (a_cursor)

	swap (i: INTEGER)
			-- Exchange_item at i-th position with item
			-- at cursor position.
			-- (from EV_DYNAMIC_LIST)
		require -- from CHAIN
			not_off: not off
			valid_index: valid_index (i)
		ensure -- from CHAIN
			swapped_to_item: item = old i_th (i)
			swapped_from_item: i_th (i) = old item
	
feature -- Removal

	prune (v: like item)
			-- Remove v if present. Do not move cursor, except if
			-- cursor was on v, move to right neighbor.
			-- (from EV_DYNAMIC_LIST)
		require -- from COLLECTION
			prunable: prunable
		ensure then -- from SET
			removed_count_change: old has (v) implies (count = old count - 1)
			not_removed_no_count_change: not old has (v) implies (count = old count)
			item_deleted: not has (v)
		ensure then -- from EV_DYNAMIC_LIST
			not_has_v: not has (v)
			had_item_implies_parent_void: old has (v) implies v.parent = void
			had_item_implies_count_decreased: old has (v) implies count = old count - 1
			had_item_and_was_after_implies_index_decreased: (old after and old has (v)) implies index = old index - 1

	prune_all (v: like item)
			-- Remove all occurrences of v.
			-- (Reference or object equality,
			-- based on object_comparison.)
			-- Leave structure exhausted.
			-- (from DYNAMIC_CHAIN)
		require -- from COLLECTION
			prunable
		ensure -- from COLLECTION
			no_more_occurrences: not has (v)
		ensure then -- from DYNAMIC_CHAIN
			is_exhausted: exhausted

	remove
			-- Remove current item. Move cursor to right neighbor.
			-- (or after if no right neighbor).
			-- (from EV_DYNAMIC_LIST)
		require -- from ACTIVE
			prunable: prunable
			writable: writable
		ensure then -- from DYNAMIC_LIST
			after_when_empty: is_empty implies after
		ensure then -- from EV_DYNAMIC_LIST
			v_removed: not has (old item)
			parent_void: (old item).parent = void
			count_decreased: count = old count - 1
			index_same: index = old index

	remove_left
			-- Remove item to left of cursor position.
			-- Do not move cursor.
			-- (from EV_DYNAMIC_LIST)
		require -- from DYNAMIC_CHAIN
			left_exists: index > 1
		require else -- from DYNAMIC_LIST
			not_before: not before
		ensure -- from DYNAMIC_CHAIN
			new_count: count = old count - 1
			new_index: index = old index - 1
		ensure then -- from EV_DYNAMIC_LIST
			left_neighbor_removed: not has (old i_th (index - 1))
			parent_void: (old i_th (index - 1)).parent = void
			index_decreased: index = old index - 1

	remove_right
			-- Remove item to right of cursor position.
			-- Do not move cursor.
			-- (from EV_DYNAMIC_LIST)
		require -- from DYNAMIC_CHAIN
			right_exists: index < count
		ensure -- from DYNAMIC_CHAIN
			new_count: count = old count - 1
			same_index: index = old index
		ensure then -- from EV_DYNAMIC_LIST
			right_neighbor_removed: not has (old i_th (index + 1))
			parent_void: (old i_th (index + 1)).parent = void
			index_same: index = old index

	wipe_out
			-- Remove all items.
			-- (from EV_DYNAMIC_LIST)
		require -- from COLLECTION
			prunable
		ensure -- from COLLECTION
			wiped_out: is_empty
		ensure then -- from DYNAMIC_LIST
			is_before: before
	
feature -- Conversion

	linear_representation: LINEAR [EV_WIDGET]
			-- Representation as a linear structure
			-- (from LINEAR)
	
feature -- Duplication

	copy (other: like Current)
			-- Update current object using fields of object attached
			-- to other, so as to yield equal objects.
			-- (from EV_ANY)
		require -- from ANY
			other_not_void: other /= void
			type_identity: same_type (other)
		ensure -- from ANY
			is_equal: is_equal (other)
	
feature -- Basic operations

	propagate_background_color
			-- Propagate background_color to all children.
			-- (from EV_CONTAINER)
		require -- from EV_CONTAINER
			not_destroyed: not is_destroyed
		ensure -- from EV_CONTAINER
			background_color_propagated: background_color_propagated

	propagate_foreground_color
			-- Propagate foreground_color to all children.
			-- (from EV_CONTAINER)
		require -- from EV_CONTAINER
			not_destroyed: not is_destroyed
		ensure -- from EV_CONTAINER
			foreground_color_propagated: foreground_color_propagated
	
feature -- Command

	destroy
			-- Destroy underlying native toolkit object.
			-- Render Current unusable.
			-- (from EV_ANY)
		ensure -- from EV_ANY
			is_destroyed: is_destroyed
	
feature -- Contract support

	same (other: EV_ANY): BOOLEAN
			-- Is other Current?
			-- (from EV_DYNAMIC_LIST)
	
feature -- Event handling

	conforming_pick_actions: EV_NOTIFY_ACTION_SEQUENCE
			-- Actions to be performed when a pebble that fits here is picked.
			-- (from EV_PICK_AND_DROPABLE_ACTION_SEQUENCES)
		ensure -- from EV_PICK_AND_DROPABLE_ACTION_SEQUENCES
			not_void: Result /= void

	drop_actions: EV_PND_ACTION_SEQUENCE
			-- Actions to be performed when a pebble is dropped here.
			-- (from EV_PICK_AND_DROPABLE_ACTION_SEQUENCES)
		ensure -- from EV_PICK_AND_DROPABLE_ACTION_SEQUENCES
			not_void: Result /= void

	focus_in_actions: EV_FOCUS_ACTION_SEQUENCE
			-- Actions to be performed when keyboard focus is gained.
			-- (from EV_WIDGET_ACTION_SEQUENCES)
		ensure -- from EV_WIDGET_ACTION_SEQUENCES
			not_void: Result /= void

	focus_out_actions: EV_FOCUS_ACTION_SEQUENCE
			-- Actions to be performed when keyboard focus is lost.
			-- (from EV_WIDGET_ACTION_SEQUENCES)
		ensure -- from EV_WIDGET_ACTION_SEQUENCES
			not_void: Result /= void

	key_press_actions: EV_KEY_ACTION_SEQUENCE
			-- Actions to be performed when a keyboard key is pressed.
			-- (from EV_WIDGET_ACTION_SEQUENCES)
		ensure -- from EV_WIDGET_ACTION_SEQUENCES
			not_void: Result /= void

	key_press_string_actions: EV_KEY_STRING_ACTION_SEQUENCE
			-- Actions to be performed when a keyboard press generates a displayable character.
			-- (from EV_WIDGET_ACTION_SEQUENCES)
		ensure -- from EV_WIDGET_ACTION_SEQUENCES
			not_void: Result /= void

	key_release_actions: EV_KEY_ACTION_SEQUENCE
			-- Actions to be performed when a keyboard key is released.
			-- (from EV_WIDGET_ACTION_SEQUENCES)
		ensure -- from EV_WIDGET_ACTION_SEQUENCES
			not_void: Result /= void

	pick_actions: EV_PND_START_ACTION_SEQUENCE
			-- Actions to be performed when pebble is picked up.
			-- (from EV_PICK_AND_DROPABLE_ACTION_SEQUENCES)
		ensure -- from EV_PICK_AND_DROPABLE_ACTION_SEQUENCES
			not_void: Result /= void

	pointer_button_press_actions: EV_POINTER_BUTTON_ACTION_SEQUENCE
			-- Actions to be performed when screen pointer button is pressed.
			-- (from EV_WIDGET_ACTION_SEQUENCES)
		ensure -- from EV_WIDGET_ACTION_SEQUENCES
			not_void: Result /= void

	pointer_button_release_actions: EV_POINTER_BUTTON_ACTION_SEQUENCE
			-- Actions to be performed when screen pointer button is released.
			-- (from EV_WIDGET_ACTION_SEQUENCES)
		ensure -- from EV_WIDGET_ACTION_SEQUENCES
			not_void: Result /= void

	pointer_double_press_actions: EV_POINTER_BUTTON_ACTION_SEQUENCE
			-- Actions to be performed when screen pointer is double clicked.
			-- (from EV_WIDGET_ACTION_SEQUENCES)
		ensure -- from EV_WIDGET_ACTION_SEQUENCES
			not_void: Result /= void

	pointer_enter_actions: EV_NOTIFY_ACTION_SEQUENCE
			-- Actions to be performed when screen pointer enters widget.
			-- (from EV_WIDGET_ACTION_SEQUENCES)
		ensure -- from EV_WIDGET_ACTION_SEQUENCES
			not_void: Result /= void

	pointer_leave_actions: EV_NOTIFY_ACTION_SEQUENCE
			-- Actions to be performed when screen pointer leaves widget.
			-- (from EV_WIDGET_ACTION_SEQUENCES)
		ensure -- from EV_WIDGET_ACTION_SEQUENCES
			not_void: Result /= void

	pointer_motion_actions: EV_POINTER_MOTION_ACTION_SEQUENCE
			-- Actions to be performed when screen pointer moves.
			-- (from EV_WIDGET_ACTION_SEQUENCES)
		ensure -- from EV_WIDGET_ACTION_SEQUENCES
			not_void: Result /= void

	resize_actions: EV_GEOMETRY_ACTION_SEQUENCE
			-- Actions to be performed when size changes.
			-- (from EV_WIDGET_ACTION_SEQUENCES)
		ensure -- from EV_WIDGET_ACTION_SEQUENCES
			not_void: Result /= void
	
feature -- Iteration

	do_all (action: PROCEDURE [ANY, TUPLE [EV_WIDGET]])
			-- Apply action to every item.
			-- Semantics not guaranteed if action changes the structure;
			-- in such a case, apply iterator to clone of structure instead.
			-- (from LINEAR)
		require -- from TRAVERSABLE
			action_exists: action /= void

	do_if (action: PROCEDURE [ANY, TUPLE [EV_WIDGET]]; test: FUNCTION [ANY, TUPLE [EV_WIDGET], BOOLEAN])
			-- Apply action to every item that satisfies test.
			-- Semantics not guaranteed if action or test changes the structure;
			-- in such a case, apply iterator to clone of structure instead.
			-- (from LINEAR)
		require -- from TRAVERSABLE
			action_exists: action /= void
			test_exits: test /= void

	for_all (test: FUNCTION [ANY, TUPLE [EV_WIDGET], BOOLEAN]): BOOLEAN
			-- Is test true for all items?
			-- (from LINEAR)
		require -- from TRAVERSABLE
			test_exits: test /= void

	there_exists (test: FUNCTION [ANY, TUPLE [EV_WIDGET], BOOLEAN]): BOOLEAN
			-- Is test true for at least one item?
			-- (from LINEAR)
		require -- from TRAVERSABLE
			test_exits: test /= void
	
feature -- Status Report

	is_destroyed: BOOLEAN
			-- Is Current no longer usable?
			-- (from EV_ANY)
		ensure -- from EV_ANY
			bridge_ok: Result = implementation.is_destroyed
	
invariant

		-- from ANY
	reflexive_equality: standard_is_equal (Current)
	reflexive_conformance: conforms_to (Current)
		-- from EV_CONTAINER
	client_width_within_bounds: is_usable implies client_width >= 0 and client_width <= width
	client_height_within_bounds: is_usable implies client_height >= 0 and client_height <= height
	all_radio_buttons_connected: is_usable implies all_radio_buttons_connected
	parent_of_items_is_current: is_usable implies parent_of_items_is_current
	items_unique: is_usable implies items_unique
		-- from EV_WIDGET
	pointer_position_not_void: is_usable and is_show_requested implies pointer_position /= void
	is_displayed_implies_show_requested: is_usable and then is_displayed implies is_show_requested
	parent_contains_current: is_usable and then parent /= void implies parent.has (Current)
		-- from EV_PICK_AND_DROPABLE
	user_interface_modes_mutually_exclusive: mode_is_pick_and_drop.to_integer + mode_is_drag_and_drop.to_integer + mode_is_target_menu.to_integer = 1
		-- from EV_ANY
	is_initialized: is_initialized
	is_coupled: implementation /= void and then implementation.interface = Current
	default_create_called: default_create_called
		-- from EV_COLORIZABLE
	background_color_not_void: is_usable implies background_color /= void
	foreground_color_not_void: is_usable implies foreground_color /= void
		-- from EV_POSITIONED
	width_not_negative: is_usable implies width >= 0
	height_not_negative: is_usable implies height >= 0
	minimum_width_not_negative: is_usable implies minimum_width >= 0
	minimum_height_not_negative: is_usable implies minimum_height >= 0
		-- from LIST
	before_definition: before = (index = 0)
	after_definition: after = (index = count + 1)
		-- from CHAIN
	non_negative_index: index >= 0
	index_small_enough: index <= count + 1
	off_definition: off = ((index = 0) or (index = count + 1))
	isfirst_definition: isfirst = ((not is_empty) and (index = 1))
	islast_definition: islast = ((not is_empty) and (index = count))
	item_corresponds_to_index: (not off) implies (item = i_th (index))
	index_set_has_same_count: index_set.count = count
		-- from ACTIVE
	writable_constraint: writable implies readable
	empty_constraint: is_empty implies (not readable) and (not writable)
		-- from INDEXABLE
	index_set_not_void: index_set /= void
		-- from BILINEAR
	not_both: not (after and before)
	before_constraint: before implies off
		-- from LINEAR
	after_constraint: after implies off
		-- from TRAVERSABLE
	empty_constraint: is_empty implies off
		-- from FINITE
	empty_definition: is_empty = (count = 0)
	non_negative_count: count >= 0
		-- from DYNAMIC_CHAIN
	extendible: extendible

end -- class EV_BOX