'From etoys4.0 of 9 October 2008 [latest update: #2212] on 4 April 2009 at 5:34:31 pm'!
"Change Set:		fixBlackScreen-yo
Date:			4 April 2009
Author:			Yoshiki Ohshima

Avoid black screen flashing when switching same-sized project with display scale enabled for both. "!


!Project methodsFor: 'initialization' stamp: 'yo 4/4/2009 17:32'!
installVirtualDisplayIfNeededFor: ext

	| actual allowance |
	allowance := 50.
	actual := Display class actualScreenSize.
	actual = OLPCVirtualScreen defaultVirtualScreenExtent ifTrue: [^ self].
	(Display isVirtualScreen and: [Display extent = ext]) ifTrue: [^ self].
	((ext x > (actual x + allowance)) or: [ext y > (actual y + allowance)]) ifTrue: [
		OLPCVirtualScreen virtualScreenExtent: ext.
		OLPCVirtualScreen install.
		^ self
	].
	((ext x <= (actual x - allowance)) and: [ext y <= (actual y - allowance)]) ifTrue: [
		OLPCVirtualScreen virtualScreenExtent: ext.
		OLPCVirtualScreen install.
		Display zoomOut: true.
		^ self.
	].

	OLPCVirtualScreen virtualScreenExtent: nil.
	OLPCVirtualScreen unInstall.
! !