There is only one instance of me, Display. It is a global and is used to handle general user requests to deal with the whole display screen.
Although I offer no protocol, my name provides a way to distinguish this special instance from all other Forms. This is useful, for example, in dealing with saving and restoring the system.
To change the depth of your Display...
Display newDepth: 16.
Display newDepth: 8.
Display newDepth: 1.
Valid display depths are 1, 2, 4, 8, 16 and 32. It is suggested that you run with your monitors setting the same, for better speed and color fidelity. Note that this can add up to 4Mb for the Display form. Finally, note that newDepth: ends by executing a 'ControlManager restore' which currently terminates the active process, so nothing that follows in the doit will get executed.

Depths 1, 2, 4 and 8 bits go through a color map to put color on the screen, but 16 and 32-bit color use the pixel values directly for RGB color (5 and 8 bits per, respectivlely). The color choice an be observed by executing Color fromUser in whatever depth you are using.

	blitter defaults
	defaultBitBltClass defaultCanvasClass defaultWarpBltClass

	disk I/O
	objectForDataStream:

	displaying
	addExtraRegion:for: copyBits:from:at:clippingBox:rule:fillColor: copyBits:from:at:clippingBox:rule:fillColor:map: flash: flash:andWait: forceDamageToScreen:

	initialize-release
	release shutDown

	other
	boundingBox clippingTo:do: deferUpdates: deferUpdatesIn:while: displayChangeSignature forceDisplayUpdate forceToScreen forceToScreen: fullBoundingBox fullScreen height newDepth: primitiveDeferUpdates: replacedBy:do: restore restoreAfter: supportedDisplayDepths supportsDisplayDepth: usableArea width

	private
	beDisplay copyFrom: findAnyDisplayDepth findAnyDisplayDepthIfNone: newDepthNoRestore: primRetryShowRectLeft:right:top:bottom: primShowRectLeft:right:top:bottom: setExtent:depth:

	testing
	isDisplayScreen

	snapshots
	actualScreenDepth actualScreenSize shutDown startUp

	blitter defaults	top
	defaultBitBltClass Return the BitBlt version to use when I am active
	defaultCanvasClass Return the WarpBlt version to use when I am active
	defaultWarpBltClass Return the WarpBlt version to use when I am active

	disk I/O	top
	objectForDataStream: I am about to be written on an object file. Write a reference to the Display in the other system instead.

	displaying	top
	addExtraRegion:for: Register the given rectangle as a region which is drawn by the specified region drawer. The region will be excluded from any updates when #forceDamageToScreen: is called. Note that the rectangle is only valid for a single update cycle; once #forceDamageToScreen: has been called, the region drawer and its region are being removed from the list
	copyBits:from:at:clippingBox:rule:fillColor: Make up a BitBlt table and copy the bits.
	copyBits:from:at:clippingBox:rule:fillColor:map: Make up a BitBlt table and copy the bits. Use a colorMap.
	flash: Flash the area of the screen defined by the given rectangle.
	flash:andWait: Flash the area of the screen defined by the given rectangle.
	forceDamageToScreen: Force all the damage rects to the screen.

	initialize-release	top
	release I am no longer Display. Release any resources if necessary
	shutDown Minimize Display memory saved in image

	other	top
	boundingBox Answer the rectangular area that represents the boundaries of the receiver's space of information.
	clippingTo:do: Display clippingTo: Rectangle fromUser do: [ScheduledControllers restore: Display fullBoundingBox]
	deferUpdates: Set the deferUpdates flag in the virtual machine. When this flag is true, BitBlt operations on the Display are not automatically propagated to the screen. If this underlying platform does not support deferred updates, this primitive will fail. Answer whether updates were deferred before if the primitive succeeds, nil if it fails.
	deferUpdatesIn:while: DisplayScreen overrides with something more involved...
	displayChangeSignature
	forceDisplayUpdate On platforms that buffer screen updates, force the screen to be updated immediately. On other platforms, or if the primitive is not implemented, do nothing.
	forceToScreen Force the entire display area to the screen
	forceToScreen: Force the given rectangular section of the Display to be copied to the screen. The primitive call does nothing if the primitive is not implemented. Typically used when the deferUpdates flag in the virtual machine is on; see deferUpdates:.
	fullBoundingBox
	fullScreen Display fullScreen
	height Answer the number that represents the height of the receiver's bounding box.
	newDepth: Display newDepth: 8. Display newDepth: 1.
	primitiveDeferUpdates: Set the deferUpdates flag in the virtual machine. When this flag is true, BitBlt operations on the Display are not automatically propagated to the screen. If this underlying platform does not support deferred updates, this primitive will fail. Answer the receiver if the primitive succeeds, nil if it fails.
	replacedBy:do: Permits normal display to draw on aForm instead of the display.
	restore
	restoreAfter: Evaluate the block, wait for a mouse click, and then restore the screen.
	supportedDisplayDepths Return all pixel depths supported on the current host platform.
	supportsDisplayDepth: Return true if this pixel depth is supported on the current host platform. Primitive. Optional.
	usableArea Answer the usable area of the receiver. 5/22/96 sw.
	width Answer the number that represents the width of the receiver's bounding box.

	private	top
	beDisplay Primitive. Tell the interpreter to use the receiver as the current display image. Fail if the form is too wide to fit on the physical display. Essential. See Object documentation whatIsAPrimitive.
	copyFrom: Take on all state of aForm, with complete sharing
	findAnyDisplayDepth Return any display depth that is supported on this system.
	findAnyDisplayDepthIfNone: Return any display depth that is supported on this system. If there is none, evaluate aBlock.
	newDepthNoRestore: Change depths. Check if there is enough space! , di
	primRetryShowRectLeft:right:top:bottom: Copy the given rectangular section of the Display to to the screen. This primitive is not implemented on all platforms. Do nothing if it fails.
	primShowRectLeft:right:top:bottom: Copy the given rectangular section of the Display to to the screen. This primitive is not implemented on all platforms. If this fails, retry integer coordinates.
	setExtent:depth: DisplayScreen startUp

	testing	top
	isDisplayScreen

	display box access	top
	boundingBox Answer the bounding box for the form representing the current display screen.
	checkForNewScreenSize Check whether the screen size has changed and if so take appropriate actions
	depth:width:height:fullscreen: Force Squeak's window (if there's one) into a new size and depth.

	snapshots	top
	actualScreenDepth
	actualScreenSize
	shutDown Minimize Display memory saved in image
	startUp DisplayScreen startUp