indexing
	description: "Eiffel Vision vertical scroll bar. Implementation interface."
	legal: "See notice at end of class."
	status: "See notice at end of class."
	date: "$Date: 2006-01-22 18:25:44 -0800 (Sun, 22 Jan 2006) $"
	revision: "$Revision: 56675 $"

deferred class interface
	EV_VERTICAL_SCROLL_BAR_I

feature -- Access

	accept_cursor: EV_POINTER_STYLE
			-- Accept cursor set by user.
			-- To be displayed when the screen pointer is over a target that accepts
			-- pebble during pick and drop.
			-- (from EV_PICK_AND_DROPABLE_I)

	actual_drop_target_agent: FUNCTION [ANY, TUPLE [INTEGER_32, INTEGER_32], EV_ABSTRACT_PICK_AND_DROPABLE]
			-- Overrides default drop target on a certain position.
			-- If `Void', will use the default drop target.
			-- Always void if `Current' is not a widget.
			-- (from EV_WIDGET_I)

	background_color: EV_COLOR
			-- Color displayed behind foregournd features.
			-- (from EV_COLORIZABLE_I)

	default_key_processing_handler: PREDICATE [ANY, TUPLE [EV_KEY]]
			-- Agent used to determine whether the default key processing should occur for `Current'.
			-- If agent returns `True' then default key processing continues as normal, False prevents
			-- default key processing from occuring.
			-- (from EV_WIDGET_I)

	deny_cursor: EV_POINTER_STYLE
			-- Deny cursor set by user.
			-- To be displayed when the screen pointer is not over a valid target.
			-- (from EV_PICK_AND_DROPABLE_I)

	foreground_color: EV_COLOR
			-- Color of foreground features like text.
			-- (from EV_COLORIZABLE_I)

	generating_type: STRING_8
			-- Name of current object's generating type
			-- (type of which it is a direct instance)
			-- (from ANY)

	generator: STRING_8
			-- Name of current object's generating class
			-- (base class of the type of which it is a direct instance)
			-- (from ANY)

	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_I)
		ensure -- from EV_HELP_CONTEXTABLE_I
			current_if_exists: internal_help_context /= Void implies Result = internal_help_context

	internal_pointer_style: EV_POINTER_STYLE
			-- Cursor displayed when screen pointer is over current widget,
			-- as seen from interface.
			-- (from EV_WIDGET_I)

	is_dock_executing: BOOLEAN
			-- Is `Current' in the process of a dockable transport?
			-- (from EV_DOCKABLE_SOURCE_I)

	is_dockable: BOOLEAN
			-- Is `Current' dockable?
			-- (from EV_DOCKABLE_SOURCE_I)

	is_external_docking_enabled: BOOLEAN
			-- Is `Current' able to be docked into an EV_DOCKABLE_DIALOG
			-- When there is no valid EV_DRAGABLE_TARGET upon completion
			-- of the transport?
			-- (from EV_DOCKABLE_SOURCE_I)

	is_external_docking_relative: BOOLEAN
			-- Will dockable dialog displayed when `Current' is docked externally
			-- be displayed relative to parent window of `Current'?
			-- Otherwise displayed as a standard window.
			-- (from EV_DOCKABLE_SOURCE_I)

	leap: INTEGER_32
			-- Value by which value is increased after leap_forward.
			-- (from EV_GAUGE_I)

	not_external_docking_enabled: BOOLEAN
			-- Attribute used for `is_externally_dockable'. We must implement
			-- `is_externally_dockable' this way as we have no easy solution to
			-- assign `True' to `is_externally_dockable'.
			-- (from EV_DOCKABLE_SOURCE_I)

	not_is_external_docking_relative: BOOLEAN
			-- Will dockable dialog displayed when `Current' is docked externally
			-- be displayed relative to parent window of `Current'?
			-- Otherwise displayed as a standard window.
			-- Internal reversed value of is_external_docking_relative as we cannot
			-- easily initialize a BOOLE to True in this case.
			-- (from EV_DOCKABLE_SOURCE_I)

	original_parent_position: INTEGER_32
			-- Original position in parent. Required
			-- to restore widget later.
			-- (from EV_DOCKABLE_SOURCE_I)

	parent: EV_CONTAINER
			-- Container widget that contains `Current'.
			-- (Void if `Current' is not in a container)
			-- (from EV_WIDGET_I)

	pebble: ANY
			-- Data to be transported by pick and drop mechanism.
			-- (from EV_PICK_AND_DROPABLE_I)

	pebble_function: FUNCTION [ANY, TUPLE, ANY]
			-- Returns data to be transported by pick and drop mechanism.
			-- (from EV_PICK_AND_DROPABLE_I)

	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_I)

	pebble_x_position: INTEGER_32
			-- Initial x position for pick and drop relative to `Current'.
			-- (from EV_PICK_AND_DROPABLE_I)

	pebble_y_position: INTEGER_32
			-- Initial y position for pick and drop relative to `Current'.
			-- (from EV_PICK_AND_DROPABLE_I)

	pointer_position: EV_COORDINATE
			-- Position of the screen pointer relative to `Current'.
			-- (from EV_WIDGET_I)
		ensure -- from EV_WIDGET_I
			result_not_void: Result /= Void

	pointer_style: EV_POINTER_STYLE
			-- Cursor displayed when screen pointer is over current widget.
			-- Void if none has been set using `set_pointer_position'.
			-- (from EV_WIDGET_I)

	real_source: EV_DOCKABLE_SOURCE
			-- `Result' is EV_DOCKABLE_SOURCE which should be
			-- dragged when docking begins on `Current'.
			-- (from EV_DOCKABLE_SOURCE_I)

	real_target: EV_DOCKABLE_TARGET
			-- `Result' is target used during a dockable transport if
			-- mouse pointer is above `Current'.
			-- (from EV_WIDGET_I)

	step: INTEGER_32
			-- Value by which value is increased after step_forward.
			-- (from EV_GAUGE_I)

	tooltip: STRING_32
			-- Tooltip displayed on `Current'.
			-- (from EV_TOOLTIPABLE_I)

	value: INTEGER_32
			-- Current value of the gauge.
			-- (from EV_GAUGE_I)

	value_range: ACTIVE_INTEGER_INTERVAL
			-- Range of value.
			-- (from EV_GAUGE_I)
	
feature -- Measurement

	height: INTEGER_32
			-- Vertical size in pixels.
			-- (from EV_POSITIONED_I)

	minimum_height: INTEGER_32
			-- Minimum vertical size in pixels.
			-- (from EV_POSITIONED_I)

	minimum_width: INTEGER_32
			-- Minimum horizontal size in pixels.
			-- (from EV_POSITIONED_I)

	screen_x: INTEGER_32
			-- Horizontal offset relative to screen.
			-- (from EV_WIDGET_I)

	screen_y: INTEGER_32
			-- Vertical offset relative to screen.
			-- (from EV_WIDGET_I)

	width: INTEGER_32
			-- Horizontal size in pixels.
			-- (from EV_POSITIONED_I)

	x_position: INTEGER_32
			-- Horizontal offset relative to parent x_position in pixels.
			-- (from EV_POSITIONED_I)

	y_position: INTEGER_32
			-- Vertical offset relative to parent y_position in pixels.
			-- (from EV_POSITIONED_I)
	
feature -- Comparison

	frozen deep_equal (some: ANY; other: like arg #1): BOOLEAN
			-- Are `some' and `other' either both void
			-- or attached to isomorphic object structures?
			-- (from ANY)
		ensure -- from ANY
			shallow_implies_deep: standard_equal (some, other) implies Result
			both_or_none_void: (some = Void) implies (Result = (other = Void))
			same_type: (Result and (some /= Void)) implies some.same_type (other)
			symmetric: Result implies deep_equal (other, some)

	frozen equal (some: ANY; other: like arg #1): BOOLEAN
			-- Are `some' and `other' either both void or attached
			-- to objects considered equal?
			-- (from ANY)
		ensure -- from ANY
			definition: Result = (some = Void and other = Void) or else ((some /= Void and other /= Void) and then some.is_equal (other))

	is_equal (other: like Current): BOOLEAN
			-- Is `other' attached to an object considered
			-- equal to current object?
			-- (from ANY)
		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

	frozen standard_equal (some: ANY; other: like arg #1): BOOLEAN
			-- Are `some' and `other' either both void or attached to
			-- field-by-field identical objects of the same type?
			-- Always uses default object comparison criterion.
			-- (from ANY)
		ensure -- from ANY
			definition: Result = (some = Void and other = Void) or else ((some /= Void and other /= Void) and then some.standard_is_equal (other))

	frozen standard_is_equal (other: like Current): BOOLEAN
			-- Is `other' attached to an object of the same type
			-- as current object, and field-by-field identical to it?
			-- (from ANY)
		require -- from ANY
			other_not_void: other /= Void
		ensure -- from ANY
			same_type: Result implies same_type (other)
			symmetric: Result implies other.standard_is_equal (Current)
	
feature -- Status report

	closest_dockable_target: EV_DOCKABLE_TARGET
			-- `Result' is first dockable target that is_dockable found by recursively
			-- searching up through the parenting structure from the widget
			-- currently underneath the pointer position.
			-- `Result' will be `Void' if a dockable target is not found.
			-- (from EV_DOCKABLE_SOURCE_I)
		ensure -- from EV_DOCKABLE_SOURCE_I
			result_is_dockable: Result /= Void implies Result.is_docking_enabled

	conforms_to (other: ANY): BOOLEAN
			-- Does type of current object conform to type
			-- of `other' (as per Eiffel: The Language, chapter 13)?
			-- (from ANY)
		require -- from ANY
			other_not_void: other /= Void

	get_next_target (a_widget: EV_WIDGET): EV_DOCKABLE_TARGET
			-- `Result' is next dockable target that is is_dockable found by
			-- recursively seraching up the parenting structure from `current_target'.
			-- `Result' will be `Void' if none.
			-- (from EV_DOCKABLE_SOURCE_I)
		require -- from EV_DOCKABLE_SOURCE_I
			a_widget_not_void: a_widget /= Void
		ensure -- from EV_DOCKABLE_SOURCE_I
			result_is_dockable: Result /= Void implies Result.is_docking_enabled

	internal_non_sensitive: BOOLEAN
			-- Is `Current' not sensitive to input as seen
			-- from interface?
			-- (from EV_SENSITIVE_I)

	is_transport_enabled: BOOLEAN
			-- Is the transport mechanism enabled?
			-- (from EV_PICK_AND_DROPABLE_I)

	mode_is_drag_and_drop: BOOLEAN
			-- Is the transport mechanism drag and drop?
			-- (from EV_PICK_AND_DROPABLE_I)

	mode_is_pick_and_drop: BOOLEAN
			-- Is the transport mechanism pick and drop?
			-- (from EV_PICK_AND_DROPABLE_I)

	mode_is_target_menu: BOOLEAN
			-- Is the transport mechanism target menu?
			-- (from EV_PICK_AND_DROPABLE_I)

	proportion: REAL_32
			-- Relative position of value in `range'. Range: [0, 1].
			-- (from EV_GAUGE_I)

	same_type (other: ANY): BOOLEAN
			-- Is type of current object identical to type of `other'?
			-- (from ANY)
		require -- from ANY
			other_not_void: other /= Void
		ensure -- from ANY
			definition: Result = (conforms_to (other) and other.conforms_to (Current))

	user_is_sensitive: BOOLEAN
			-- Is the object sensitive to user input.
			-- (from EV_SENSITIVE_I)
	
feature -- Status setting

	disable_dockable
			-- Ensure `Current' is not dockable
			-- (from EV_DOCKABLE_SOURCE_I)
		ensure -- from EV_DOCKABLE_SOURCE_I
			not_is_dockable: not is_dockable

	disable_external_docking
			-- Forbid `Current' to be docked into an EV_DOCKABLE_DIALOG
			-- When there is no valid EV_DRAGABLE_TARGET upon completion
			-- of the transport?
			-- (from EV_DOCKABLE_SOURCE_I)
		require -- from EV_DOCKABLE_SOURCE_I
			is_dockable: is_dockable
		ensure -- from EV_DOCKABLE_SOURCE_I
			not_externally_dockable: not is_external_docking_enabled

	disable_external_docking_relative
			-- Assign `False' to is_external_docking_relative, ensuring that
			-- a dockable dialog displayed when `Current' is docked externally
			-- is displayed as a standard window.
			-- (from EV_DOCKABLE_SOURCE_I)
		require -- from EV_DOCKABLE_SOURCE_I
			external_docking_enabled: is_external_docking_enabled
		ensure -- from EV_DOCKABLE_SOURCE_I
			external_docking_not_relative: not is_external_docking_relative

	disable_pebble_positioning
			-- Assign `False' to pebble_positioning_enabled.
			-- (from EV_PICK_AND_DROPABLE_I)

	disable_transport
			-- Deactivate pick/drag and drop mechanism.
			-- (from EV_PICK_AND_DROPABLE_I)
		ensure -- from EV_PICK_AND_DROPABLE_I
			is_transport_disabled: not is_transport_enabled

	enable_dockable
			-- Allow `Current' to be dockable
			-- (from EV_DOCKABLE_SOURCE_I)
		ensure -- from EV_DOCKABLE_SOURCE_I
			is_dockable: is_dockable

	enable_external_docking
			-- Allow `Current' to be docked into an EV_DOCKABLE_DIALOG
			-- When there is no valid EV_DRAGABLE_TARGET upon completion
			-- of the transport?
			-- (from EV_DOCKABLE_SOURCE_I)
		require -- from EV_DOCKABLE_SOURCE_I
			is_dockable: is_dockable
		ensure -- from EV_DOCKABLE_SOURCE_I
			is_externally_dockable: is_external_docking_enabled

	enable_external_docking_relative
			-- Assign `True' to is_external_docking_relative, ensuring that
			-- a dockable dialog displayed when `Current' is docked externally
			-- is displayed relative to the top level window.
			-- (from EV_DOCKABLE_SOURCE_I)
		require -- from EV_DOCKABLE_SOURCE_I
			external_docking_enabled: is_external_docking_enabled
		ensure -- from EV_DOCKABLE_SOURCE_I
			external_docking_not_relative: is_external_docking_relative

	enable_pebble_positioning
			-- Assign `True' to pebble_positioning_enabled.
			-- (from EV_PICK_AND_DROPABLE_I)

	enable_transport
			-- Activate pick/drag and drop mechanism.
			-- (from EV_PICK_AND_DROPABLE_I)
		require -- from EV_PICK_AND_DROPABLE_I
			pebble_not_void: pebble /= Void or pebble_function /= Void
		ensure -- from EV_PICK_AND_DROPABLE_I
			is_transport_enabled: interface.implementation.is_transport_enabled

	hide
			-- Request that `Current' not be displayed when its parent is.
			-- (from EV_WIDGET_I)

	internal_disable_dockable
			-- Platform specific implementation of disable_dockable.
			-- (from EV_DOCKABLE_SOURCE_I)

	internal_enable_dockable
			-- Platform specific implementation of enable_dockable.
			-- (from EV_DOCKABLE_SOURCE_I)

	leap_backward
			-- Decrement value by leap if possible.
			-- (from EV_GAUGE_I)
		ensure -- from EV_GAUGE_I
			decremented: value = old value - leap or else value = value_range.lower

	leap_forward
			-- Increment value by leap if possible.
			-- (from EV_GAUGE_I)
		ensure -- from EV_GAUGE_I
			incremented: value = old value + leap or else value = value_range.upper

	remove_default_key_processing_handler
			-- Ensure default_key_processing_handler is Void.
			-- (from EV_WIDGET_I)
		ensure -- from EV_WIDGET_I
			default_key_processing_handler_removed: default_key_processing_handler = Void

	remove_pebble
			-- Remove pebble.
			-- (from EV_PICK_AND_DROPABLE_I)
		ensure -- from EV_PICK_AND_DROPABLE_I
			pebble_removed: pebble = Void and pebble_function = Void
			is_transport_disabled: not is_transport_enabled

	remove_real_source
			-- Ensure real_source is `Void'.
			-- (from EV_DOCKABLE_SOURCE_I)
		require -- from EV_DOCKABLE_SOURCE_I
			is_dockable: is_dockable
		ensure -- from EV_DOCKABLE_SOURCE_I
			real_source_void: real_source = Void

	remove_real_target
			-- Ensure real_target is `Void'.
			-- (from EV_WIDGET_I)
		ensure -- from EV_WIDGET_I
			real_target_void: real_target = Void

	set_accept_cursor (a_cursor: like accept_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_I)

	set_actual_drop_target_agent (an_agent: like actual_drop_target_agent)
			-- Assign `an_agent' to actual_drop_target_agent.
			-- (from EV_WIDGET_I)
		require -- from EV_WIDGET_I
			an_agent_not_void: an_agent /= Void
		ensure -- from EV_WIDGET_I
			assigned: actual_drop_target_agent = an_agent

	set_default_colors
			-- Set foreground and background color to their default values.
			-- (from EV_COLORIZABLE_I)

	set_default_key_processing_handler (a_handler: like default_key_processing_handler)
			-- Assign default_key_processing_handler to `a_handler'.
			-- (from EV_WIDGET_I)

	set_deny_cursor (a_cursor: like deny_cursor)
			-- Set `a_cursor' to be displayed when the screen pointer is over a
			-- target that doesn't accept pebble during pick and drop.
			-- (from EV_PICK_AND_DROPABLE_I)

	set_drag_and_drop_mode
			-- Set transport mechanism to drag and drop,
			-- (from EV_PICK_AND_DROPABLE_I)
		ensure -- from EV_PICK_AND_DROPABLE_I
			mode_is_drag_and_drop: mode_is_drag_and_drop

	set_focus
			-- Grab keyboard focus.
			-- (from EV_WIDGET_I)

	set_pebble (a_pebble: like pebble)
			-- Assign `a_pebble' to pebble.
			-- (from EV_PICK_AND_DROPABLE_I)
		require -- from EV_PICK_AND_DROPABLE_I
			a_pebble_not_void: a_pebble /= Void
		ensure -- from EV_PICK_AND_DROPABLE_I
			pebble_assigned: interface.implementation.pebble = a_pebble
			is_transport_enabled: interface.implementation.is_transport_enabled

	set_pebble_function (a_function: FUNCTION [ANY, TUPLE, ANY])
			-- Assign `a_function' to pebble_function.
			-- (from EV_PICK_AND_DROPABLE_I)
		require -- from EV_PICK_AND_DROPABLE_I
			a_function_not_void: a_function /= Void
		ensure -- from EV_PICK_AND_DROPABLE_I
			pebble_function_assigned: interface.implementation.pebble_function = a_function
			is_transport_enabled: interface.implementation.is_transport_enabled

	set_pebble_position (a_x, a_y: INTEGER_32)
			-- Set the initial position for pick and drop relative to `Current'.
			-- (from EV_PICK_AND_DROPABLE_I)
		ensure -- from EV_PICK_AND_DROPABLE_I
			pick_x_assigned: pick_x = a_x
			pick_y_assigned: pick_y = a_y

	set_pick_and_drop_mode
			-- Set transport mechanism to pick and drop,
			-- (from EV_PICK_AND_DROPABLE_I)
		ensure -- from EV_PICK_AND_DROPABLE_I
			mode_is_pick_and_drop: mode_is_pick_and_drop

	set_proportion (a_proportion: REAL_32)
			-- Move value to `a_proportion' within `range'.
			-- (from EV_GAUGE_I)
		require -- from EV_GAUGE_I
			a_proportion_within_range: a_proportion >= 0 and a_proportion <= 1

	set_real_source (dockable_source: EV_DOCKABLE_SOURCE)
			-- Set `dockable_source' to be the widget moved when a
			-- drag begins on `Current'.
			-- (from EV_DOCKABLE_SOURCE_I)
		require -- from EV_DOCKABLE_SOURCE_I
			is_dockable: is_dockable
			dockable_source_not_void: dockable_source /= Void
		ensure -- from EV_DOCKABLE_SOURCE_I
			real_source_assigned: real_source = dockable_source

	set_real_target (a_target: EV_DOCKABLE_TARGET)
			-- Assign `a_target' to real_target.
			-- (from EV_WIDGET_I)
		require -- from EV_WIDGET_I
			target_not_void: a_target /= Void
		ensure -- from EV_WIDGET_I
			assigned: real_target = a_target

	set_target_menu_mode
			-- Set transport mechanism to target_menu.
			-- (from EV_PICK_AND_DROPABLE_I)
		ensure -- from EV_PICK_AND_DROPABLE_I
			mode_is_target_menu: mode_is_target_menu

	show
			-- Request that `Current' be displayed when its parent is.
			-- (from EV_WIDGET_I)

	step_backward
			-- Decrement value by step if possible.
			-- (from EV_GAUGE_I)
		ensure -- from EV_GAUGE_I
			decremented: value = old value - step or else value = value_range.lower

	step_forward
			-- Increment value by step if possible.
			-- (from EV_GAUGE_I)
		ensure -- from EV_GAUGE_I
			incremented: value = old value + step or else value = value_range.upper

	user_disable_sensitive
			-- Make object desensitive to user input.
			-- (from EV_SENSITIVE_I)
		ensure -- from EV_SENSITIVE_I
			is_desensitive: not user_is_sensitive

	user_enable_sensitive
			-- Make object sensitive to user input.
			-- (from EV_SENSITIVE_I)
		ensure -- from EV_SENSITIVE_I
			is_sensitive_if_parent_sensitive: (has_parent and then parent_is_sensitive) implies interface.implementation.is_sensitive
			is_sensitive_if_orphaned: not has_parent implies interface.implementation.is_sensitive
	
feature -- Element change

	remove_help_context
			-- Remove key press action associated with `EV_APPLICATION.help_key'.
			-- (from EV_HELP_CONTEXTABLE_I)
		require -- from EV_HELP_CONTEXTABLE_I
			help_context_not_void: help_context /= Void
		ensure -- from EV_HELP_CONTEXTABLE_I
			no_help_context: internal_help_context = Void

	set_background_color (a_color: like background_color)
			-- Assign `a_color' to foreground_color.
			-- (from EV_COLORIZABLE_I)
		require -- from EV_COLORIZABLE_I
			a_color_not_void: a_color /= Void
		ensure -- from EV_COLORIZABLE_I
			background_color_assigned: is_initialized implies interface.implementation.background_color.is_equal (a_color)

	set_foreground_color (a_color: like foreground_color)
			-- Assign `a_color' to foreground_color.
			-- (from EV_COLORIZABLE_I)
		require -- from EV_COLORIZABLE_I
			a_color_not_void: a_color /= Void
		ensure -- from EV_COLORIZABLE_I
			foreground_color_assigned: is_initialized implies interface.implementation.foreground_color.is_equal (a_color)

	set_help_context (an_help_context: like help_context)
			-- Assign `a_help_context' to help_context.
			-- Assign `an_help_context' to help_context.
			-- (from EV_HELP_CONTEXTABLE_I)
		require -- from EV_HELP_CONTEXTABLE_I
			an_help_context_not_void: an_help_context /= Void
		ensure -- from EV_HELP_CONTEXTABLE_I
			help_context_assigned: help_context.is_equal (an_help_context)

	set_leap (a_leap: INTEGER_32)
			-- Set leap to `a_leap'.
			-- (from EV_GAUGE_I)
		require -- from EV_GAUGE_I
			a_leap_non_negative: a_leap > 0
		ensure -- from EV_GAUGE_I
			assigned: leap = a_leap

	set_minimum_height (a_minimum_height: INTEGER_32)
			-- Set the minimum vertical size to `a_minimum_height' in pixels.
			-- (from EV_WIDGET_I)
		require -- from EV_WIDGET_I
			a_minimum_height_positive: a_minimum_height >= 0
		ensure -- from EV_WIDGET_I
			minimum_height_assigned: is_usable implies interface.minimum_height = a_minimum_height

	set_minimum_size (a_minimum_width, a_minimum_height: INTEGER_32)
			-- Set the minimum horizontal size to `a_minimum_width' in pixels.
			-- Set the minimum vertical size to `a_minimum_height' in pixels.
			-- (from EV_WIDGET_I)
		require -- from EV_WIDGET_I
			a_minimum_width_positive: a_minimum_width >= 0
			a_minimum_height_positive: a_minimum_height >= 0
		ensure -- from EV_WIDGET_I
			minimum_width_assigned: is_usable implies interface.minimum_width = a_minimum_width
			minimum_height_assigned: is_usable implies interface.minimum_height = a_minimum_height

	set_minimum_width (a_minimum_width: INTEGER_32)
			-- Set the minimum horizontal size to `a_minimum_width' in pixels.
			-- (from EV_WIDGET_I)
		require -- from EV_WIDGET_I
			a_minimum_width_positive: a_minimum_width >= 0
		ensure -- from EV_WIDGET_I
			minimum_width_assigned: is_usable implies interface.minimum_width = a_minimum_width

	set_step (a_step: INTEGER_32)
			-- Set step to `a_step'.
			-- (from EV_GAUGE_I)
		require -- from EV_GAUGE_I
			a_step_positive: a_step > 0
		ensure -- from EV_GAUGE_I
			assigned: step = a_step

	set_tooltip (a_tooltip: STRING_GENERAL)
			-- Assign `a_tooltip' to tooltip.
			-- (from EV_TOOLTIPABLE_I)
		require -- from EV_TOOLTIPABLE_I
			a_tooltip_not_void: a_tooltip /= Void

	set_value (a_value: INTEGER_32)
			-- Set value to `a_value'.
			-- (from EV_GAUGE_I)
		require -- from EV_GAUGE_I
			value_in_range: value_range.has (a_value)
		ensure -- from EV_GAUGE_I
			assigned: value = a_value
	
feature -- Duplication

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

	frozen deep_copy (other: like Current)
			-- Effect equivalent to that of:
			--		copy (`other' . deep_twin)
			-- (from ANY)
		require -- from ANY
			other_not_void: other /= Void
		ensure -- from ANY
			deep_equal: deep_equal (Current, other)

	frozen deep_twin: like Current
			-- New object structure recursively duplicated from Current.
			-- (from ANY)
		ensure -- from ANY
			deep_equal: deep_equal (Current, Result)

	frozen standard_copy (other: like Current)
			-- Copy every field of `other' onto corresponding field
			-- of current object.
			-- (from ANY)
		require -- from ANY
			other_not_void: other /= Void
			type_identity: same_type (other)
		ensure -- from ANY
			is_standard_equal: standard_is_equal (other)

	frozen standard_twin: like Current
			-- New object field-by-field identical to `other'.
			-- Always uses default copying semantics.
			-- (from ANY)
		ensure -- from ANY
			standard_twin_not_void: Result /= Void
			equal: standard_equal (Result, Current)

	frozen twin: like Current
			-- New object equal to `Current'
			-- twin calls copy; to change copying/twining semantics, redefine copy.
			-- (from ANY)
		ensure -- from ANY
			twin_not_void: Result /= Void
			is_equal: Result.is_equal (Current)
	
feature -- Basic operations

	close_dockable_dialog (dockable_dialog: EV_DOCKABLE_DIALOG)
			-- Close request received by `dockable_dialog' so
			-- restore widget contained back to its original position
			-- in its old parent if possible.
			-- We must fire `dock_ended' actions.
			-- (from EV_DOCKABLE_SOURCE_I)
		ensure -- from EV_DOCKABLE_SOURCE_I
			dockable_dialog_destroyed: dockable_dialog.is_destroyed

	complete_dock
			-- Complete a dock from source_being_docked.
			-- (from EV_DOCKABLE_SOURCE_I)
		require -- from EV_DOCKABLE_SOURCE_I
			source_being_docked: source_being_docked /= Void
		ensure -- from EV_DOCKABLE_SOURCE_I
			not_dock_executing: not is_dock_executing
			insert_separator_not_parented: insert_sep.parent = Void
			insert_label_not_parented: insert_label.parent = Void

	frozen default: like Current
			-- Default value of object's type
			-- (from ANY)

	frozen default_pointer: POINTER
			-- Default value of type `POINTER'
			-- (Avoid the need to write `p'.default for
			-- some `p' of type `POINTER'.)
			-- (from ANY)

	default_rescue
			-- Process exception for routines with no Rescue clause.
			-- (Default: do nothing.)
			-- (from ANY)

	frozen do_nothing
			-- Execute a null action.
			-- (from ANY)

	refresh_now
			-- Force an immediate redraw of `Current'.
			-- (from EV_WIDGET_I)
	
feature -- Inapplicable

	drag_cursor: EV_POINTER_STYLE
			-- Cursor used when `Current' is being transported.
			-- (from EV_DOCKABLE_SOURCE_I)
	
feature -- Access EV_DRAGABLE_SOURCE.

	dockable_dialog_target: EV_DOCKABLE_DIALOG
			-- A dockable dialog that will be created as
			-- necessary. This is not a local, to avoid it
			-- being garbage collected.
			-- (from EV_SHARED_TRANSPORT_I)

	global_drag_targets: ARRAYED_LIST [INTEGER_32]
			-- Shortcut to EV_APPLICATION.pnd_targets.
			-- (from EV_SHARED_TRANSPORT_I)

	insert_label: EV_CELL
			-- Label used to indicate where `Current' will be placed in target.
			-- (from EV_SHARED_TRANSPORT_I)
		ensure -- from EV_SHARED_TRANSPORT_I
			result_not_void: Result /= Void

	insert_label_imp: EV_CELL_I
			-- Once access to implementation of Insert_label.
			-- (from EV_SHARED_TRANSPORT_I)
		ensure -- from EV_SHARED_TRANSPORT_I
			Result /= Void

	insert_sep: EV_TOOL_BAR_SEPARATOR
			-- Once access to a separator used to indicate the insertion position
			-- when moving tool bar items.
			-- (from EV_SHARED_TRANSPORT_I)

	insert_sep_imp: EV_TOOL_BAR_SEPARATOR_I
			-- Once access to implementation of Insert_sep.
			-- (from EV_SHARED_TRANSPORT_I)
		ensure -- from EV_SHARED_TRANSPORT_I
			Result /= Void

	internal_screen: EV_SCREEN
			-- Once access to an EV_SCREEN.
			-- (from EV_SHARED_TRANSPORT_I)

	original_x_offset: INTEGER_16
			-- Original x_offset and original_y_offset of transport
			-- realtive to widget. Only used for dragable transports.
			-- (from EV_SHARED_TRANSPORT_I)

	original_y_offset: INTEGER_16
			-- Original x_offset and original_y_offset of transport
			-- realtive to widget. Only used for dragable transports.
			-- (from EV_SHARED_TRANSPORT_I)

	originating_source: EV_DOCKABLE_SOURCE_I
			-- Dragable source that originated the transport of `source_being_dragged'.
			-- (from EV_SHARED_TRANSPORT_I)

	remove_insert_label
			-- Remove Insert_label from its current parent.
			-- We must handle a special case for cells. If the parent is a cell,
			-- then we remove the cell from its parent, and then restore it.
			-- Otherwise, when the label, removed, the cell keeps it size, and cells
			-- are normally used with real_target when the cell must
			-- not be visible.
			-- (from EV_SHARED_TRANSPORT_I)
		ensure -- from EV_SHARED_TRANSPORT_I
			not_parented: insert_label.parent = Void

	remove_insert_sep
			-- Ensure `inset_sep' is not parented.
			-- (from EV_SHARED_TRANSPORT_I)
		ensure -- from EV_SHARED_TRANSPORT_I
			not_parented: insert_sep.parent = Void

	source_being_docked: EV_DOCKABLE_SOURCE_I
			-- Dragable source currently being transported. May be a
			-- WIDGET_IMP or an EV_TOOL_BAR_BUTTON_IMP.
			-- (from EV_SHARED_TRANSPORT_I)
	
feature -- Access EV_PICK_AND_DROPABLE.

	default_accept_cursor: EV_POINTER_STYLE
			-- Used in lieu of a user defined accept_cursor.
			-- (from EV_SHARED_TRANSPORT_I)

	default_deny_cursor: EV_POINTER_STYLE
			-- Used in lieu of a user defined deny_cursor.
			-- (from EV_SHARED_TRANSPORT_I)

	default_pixmaps: EV_STOCK_PIXMAPS
			-- Default pixmaps
			-- (from EV_SHARED_TRANSPORT_I)

	global_pnd_targets: HASH_TABLE [INTEGER_32, INTEGER_32]
			-- Shortcut to EV_APPLICATION.pnd_targets.
			-- (from EV_SHARED_TRANSPORT_I)

	rubber_band_is_drawn: BOOLEAN
			-- Is a rubber band line currently on the screen?
			-- (from EV_SHARED_TRANSPORT_I)
	
feature -- Access common.

	pointer_x: INTEGER_16
			-- (from EV_SHARED_TRANSPORT_I)

	pointer_y: INTEGER_16
			-- (from EV_SHARED_TRANSPORT_I)
	
feature -- Event handling

	change_actions: EV_VALUE_CHANGE_ACTION_SEQUENCE
			-- Actions to be performed when value changes.
			-- (from EV_GAUGE_ACTION_SEQUENCES_I)
		ensure -- from EV_GAUGE_ACTION_SEQUENCES_I
			not_void: Result /= Void

	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_I)
		ensure -- from EV_PICK_AND_DROPABLE_ACTION_SEQUENCES_I
			not_void: Result /= Void

	dock_ended_actions: EV_NOTIFY_ACTION_SEQUENCE
			-- Actions to be performed after a dock completes from `Current'.
			-- Either to a dockable target or a dockable dialog.
			-- (from EV_DOCKABLE_SOURCE_ACTION_SEQUENCES_I)
		ensure -- from EV_DOCKABLE_SOURCE_ACTION_SEQUENCES_I
			not_void: Result /= Void

	dock_started_actions: EV_NOTIFY_ACTION_SEQUENCE
			-- Actions to be performed when pebble is picked up.
			-- (from EV_DOCKABLE_SOURCE_ACTION_SEQUENCES_I)
		ensure -- from EV_DOCKABLE_SOURCE_ACTION_SEQUENCES_I
			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_I)
		ensure -- from EV_PICK_AND_DROPABLE_ACTION_SEQUENCES_I
			not_void: Result /= Void

	file_drop_actions: ACTION_SEQUENCE [TUPLE [LIST [STRING_32]]]
			-- Actions to be performed when an OS file drop occurs on `Current'.
			-- (from EV_WIDGET_ACTION_SEQUENCES_I)
		ensure -- from EV_WIDGET_ACTION_SEQUENCES_I
			not_void: Result /= Void

	focus_in_actions: EV_NOTIFY_ACTION_SEQUENCE
			-- Actions to be performed when keyboard focus is gained.
			-- (from EV_WIDGET_ACTION_SEQUENCES_I)
		ensure -- from EV_WIDGET_ACTION_SEQUENCES_I
			not_void: Result /= Void

	focus_out_actions: EV_NOTIFY_ACTION_SEQUENCE
			-- Actions to be performed when keyboard focus is lost.
			-- (from EV_WIDGET_ACTION_SEQUENCES_I)
		ensure -- from EV_WIDGET_ACTION_SEQUENCES_I
			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_I)
		ensure -- from EV_WIDGET_ACTION_SEQUENCES_I
			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_I)
		ensure -- from EV_WIDGET_ACTION_SEQUENCES_I
			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_I)
		ensure -- from EV_WIDGET_ACTION_SEQUENCES_I
			not_void: Result /= Void

	mouse_wheel_actions: EV_INTEGER_ACTION_SEQUENCE
			-- Actions to be performed when mouse wheel is rotated.
			-- (from EV_WIDGET_ACTION_SEQUENCES_I)
		ensure -- from EV_WIDGET_ACTION_SEQUENCES_I
			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_I)
		ensure -- from EV_PICK_AND_DROPABLE_ACTION_SEQUENCES_I
			not_void: Result /= Void

	pick_ended_actions: EV_PND_FINISHED_ACTION_SEQUENCE
			-- Actions to be performed when a transport from `Current' ends.
			-- (from EV_PICK_AND_DROPABLE_ACTION_SEQUENCES_I)
		ensure -- from EV_PICK_AND_DROPABLE_ACTION_SEQUENCES_I
			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_I)
		ensure -- from EV_WIDGET_ACTION_SEQUENCES_I
			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_I)
		ensure -- from EV_WIDGET_ACTION_SEQUENCES_I
			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_I)
		ensure -- from EV_WIDGET_ACTION_SEQUENCES_I
			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_I)
		ensure -- from EV_WIDGET_ACTION_SEQUENCES_I
			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_I)
		ensure -- from EV_WIDGET_ACTION_SEQUENCES_I
			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_I)
		ensure -- from EV_WIDGET_ACTION_SEQUENCES_I
			not_void: Result /= Void

	resize_actions: EV_GEOMETRY_ACTION_SEQUENCE
			-- Actions to be performed when size changes.
			-- (from EV_WIDGET_ACTION_SEQUENCES_I)
		ensure -- from EV_WIDGET_ACTION_SEQUENCES_I
			not_void: Result /= Void
	
feature -- Output

	io: STD_FILES
			-- Handle to standard file setup
			-- (from ANY)

	out: STRING_8
			-- New string containing terse printable representation
			-- of current object
			-- Was declared in ANY as synonym of tagged_out.
			-- (from ANY)

	print (some: ANY)
			-- Write terse external representation of `some'
			-- on standard output.
			-- (from ANY)

	frozen tagged_out: STRING_8
			-- New string containing terse printable representation
			-- of current object
			-- Was declared in ANY as synonym of out.
			-- (from ANY)
	
feature -- Platform

	operating_environment: OPERATING_ENVIRONMENT
			-- Objects available from the operating system
			-- (from ANY)
	
feature -- Status Report

	has_capture: BOOLEAN
			-- Does widget have capture?
			-- (from EV_WIDGET_I)

	has_focus: BOOLEAN
			-- Does widget have the keyboard focus?
			-- (from EV_WIDGET_I)

	is_displayed: BOOLEAN
			-- Is `Current' visible on the screen?
			-- False if `Current' is entirely obscured by another window.
			-- (from EV_WIDGET_I)

	is_show_requested: BOOLEAN
			-- Will `Current' be displayed when its parent is?
			-- See also is_displayed.
			-- (from EV_WIDGET_I)
	
invariant
		-- from EV_GAUGE_I
	value_range_not_void: is_usable implies value_range /= Void

		-- from EV_WIDGET_I
	is_displayed_implies_show_requested: is_usable and is_displayed implies is_show_requested

		-- from EV_PICK_AND_DROPABLE_I
	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
	pebble_function_takes_two_integer_open_operands: pebble_function /= Void implies pebble_function.valid_operands ([1, 1])

		-- from EV_ANY_I
	interface_coupled: is_usable implies interface /= Void and then interface.implementation = Current
	base_make_called: base_make_called

		-- from ANY
	reflexive_equality: standard_is_equal (Current)
	reflexive_conformance: conforms_to (Current)

		-- from EV_DOCKABLE_SOURCE_I
	widget_or_item_source: not (widget_source_being_docked /= Void and item_source_being_docked /= Void)
	dock_executing: is_dock_executing implies widget_source_being_docked /= Void or item_source_being_docked /= Void

		-- from EV_POSITIONED_I
	minimum_width_positive_or_zero: is_usable implies minimum_width >= 0
	minimum_height_positive_or_zero: is_usable implies minimum_height >= 0

indexing
	copyright: "Copyright (c) 1984-2006, Eiffel Software and others"
	license: "Eiffel Forum License v2 (see http://www.eiffel.com/licensing/forum.txt)"
	source: "[
		Eiffel Software
		356 Storke Road, Goleta, CA 93117 USA
		Telephone 805-685-1006, Fax 805-685-6869
		Website http://www.eiffel.com
		Customer support http://support.eiffel.com
	]"

end -- class EV_VERTICAL_SCROLL_BAR_I