A PluggableButtonView is a combination of an indicator for a boolean value stored in its model and an action button. The action of a button is often, but not always, to toggle the boolean value that it shows. Its pluggable selectors are:

getStateSelector fetch a boolean value from the model
actionSelector invoke this button's action on the model

Either of the above selectors can be nil, meaning that the model does not supply behavior for the given action, and the default behavior should be used. For example, if getStateSelector is nil, then this button shows the state of a read-only boolean that is always false.

The model informs a pluggable view of changes by sending #changed: to itself with getStateSelector as a parameter. The view tells the model when the button is pressed by sending actionSelector.

Options:
askBeforeChanging have model ask user before allowing change that could lose edits
triggerOnMouseDown do button action on mouse down (vs. up) transition
shortcutCharacter a place to record an optional shortcut key

	controller access
	defaultControllerClass

	displaying
	deEmphasizeView display displayComplemented displayNormal displayView emphasizeView toggleMouseOverFeedback

	initialize-release
	initialize on:getState:action:label:menu:

	other
	defaultWindow performAction update: window:

	private
	centerAlignLabelWith: centerLabel getMenu: getModelState insetDisplayBox

	instance creation
	on: on:getState:action: on:getState:action:label: on:getState:action:label:menu:

	accessing	top
	action: Set actionSelector to be the action defined by aSymbol.
	askBeforeChanging
	askBeforeChanging: If this preference is turned on, then give the model an opportunity to ask the user before accepting a change that might cause unaccepted edits to be lost.
	label Answer the DisplayObject used as this button's label.
	label: Label this button with the given String or DisplayObject.
	shortcutCharacter Return the Character to be used as a shortcut to turn on this switch, or nil if this switch doesn't have a keyboard shortcut.
	shortcutCharacter: Set the character to be used as a keyboard shortcut for turning on this switch.
	triggerOnMouseDown
	triggerOnMouseDown: If this preference is turned on, then trigger my action immediately when the mouse goes down.

	controller access	top
	defaultControllerClass Answer the class of the default controller for the receiver. Subclasses should redefine View|defaultControllerClass if the class of the default controller is not Controller.

	displaying	top
	deEmphasizeView Subclasses should redefine View|deEmphasizeView in order to modify the emphasis (highlighting, special tabs) of particular objects associated with the View such as labels, lines, and boxes.
	display Sets the PluggableButtonView mode to 'normal', displays the border, displays the inside and, if its model is 'on', complements the inside.
	displayComplemented Complement the receiver if it isn't already.
	displayNormal Complement the receiver if its mode is 'complemented'.
	displayView Displays this switch and its label, if any.
	emphasizeView Subclasses should redefine View|emphasizeView in order to modify the emphasis (highlighting, special tabs) of particular objects associated with the View such as labels, lines, and boxes.
	toggleMouseOverFeedback Complement the label (or a portion of the displayBox if no label is defined) to show that the mouse is over this button. This feedback can be removed by a second call to this method.

	initialize-release	top
	initialize Initialize the state of the receiver. Subclasses should include 'super initialize' when redefining this message to insure proper initialization.
	on:getState:action:label:menu:

	other	top
	defaultWindow Return a rectangle large enough to contain this button's label. If this button is label-less, just return the standard View default window.
	performAction Inform the model that this button has been pressed. Sent by the controller when this button is pressed.
	update: Normally sent by the receiver's model in order to notify the receiver of a change in the model's state. Subclasses implement this message to do particular update actions. A typical action that might be required is to redisplay the receiver.
	window: Center my label when my window changes.

	private	top
	centerAlignLabelWith: Align the center of the label with aPoint.
	centerLabel If there is a label, align its center with the center of the insetDisplayBox
	getMenu: Answer the menu for this view, supplying an empty menu to be filled in. If the menu selector takes an extra argument, pass in the current state of the shift key.
	getModelState Answer the result of sending the receiver's model the getStateSelector message.
	insetDisplayBox Answer the receiver's inset display box. The inset display box is the intersection of the receiver's window, tranformed to display coordinates, and the inset display box of the superView, inset by the border width. The inset display box represents the region of the display screen in which the inside of the receiver (all except the border) is displayed. If the receiver is totally clipped by the display screen and its superView, the resulting Rectangle will be invalid.

	example	top
	example PluggableButtonView example

	instance creation	top
	on:
	on:getState:action:
	on:getState:action:label:
	on:getState:action:label:menu: