Chris Muller uploaded a new version of Morphic to project The Trunk:
http://source.squeak.org/trunk/Morphic-cmm.680.mcz

==================== Summary ====================

Name: Morphic-cmm.680
Author: cmm
Time: 10 September 2013, 1:10:23.389 pm
UUID: 8b69c5f3-2a26-41ef-9584-ff0fbb507626
Ancestors: Morphic-cmm.679

Tame the twitching scenario when using Smart Splitters.

=============== Diff against Morphic-cmm.679 ===============

Item was changed:
  ----- Method: PluggableListMorph>>visibleList (in category 'accessing') -----
  visibleList
- 	"Fix this to return just the items that are in the list."
  	^ list isEmptyOrNil
  		ifTrue: [ Array empty ]
  		ifFalse:
  			[ list
  				copyFrom: self topVisibleRowIndex
  				to: (self bottomVisibleRowIndex min: list size) ]!

Item was changed:
  AbstractResizerMorph subclass: #ProportionalSplitterMorph
+ 	instanceVariableNames: 'leftOrTop rightOrBottom splitsTopAndBottom oldColor traceMorph handle movements'
- 	instanceVariableNames: 'leftOrTop rightOrBottom splitsTopAndBottom oldColor traceMorph handle'
  	classVariableNames: 'SmartHorizontalSplitters SmartVerticalSplitters'
  	poolDictionaries: ''
  	category: 'Morphic-Windows'!
  
  !ProportionalSplitterMorph commentStamp: 'jmv 1/29/2006 17:16' prior: 0!
  I am the morph the user grabs to adjust pane splitters.!

Item was changed:
  ----- Method: ProportionalSplitterMorph>>initialize (in category 'initialization') -----
  initialize
  
  	super initialize.
  	
  	self hResizing: #spaceFill.
  	self vResizing: #spaceFill.
  	splitsTopAndBottom := false.
  	
  	leftOrTop := OrderedCollection new.
  	rightOrBottom := OrderedCollection new.
  	
  	Preferences showSplitterHandles 
  		ifTrue: [
  			handle := CircleMorph new
  					borderWidth: 0;
  					extent: 4 at 4;
  					yourself.
  			handle fillStyle: ((GradientFillStyle 
  						ramp: {0.0 -> Preferences defaultWindowColor muchLighter. 
  							1.0 -> Preferences defaultWindowColor darker})
  						origin: handle topLeft;
  						direction: 0 @ handle bounds extent y;
  						normal: handle bounds extent x @ 0;
  						radial: false;
  						yourself).
+ 			self addMorphCentered: handle].
+ 	self initializeMovements!
- 			self addMorphCentered: handle].!

Item was added:
+ ----- Method: ProportionalSplitterMorph>>initializeMovements (in category 'initialization') -----
+ initializeMovements
+ 	movements := OrderedCollection with: 0 with: 0 with: 0!

Item was added:
+ ----- Method: ProportionalSplitterMorph>>movements (in category 'layout') -----
+ movements
+ 	"Used to track my pattern of movement for the last 3 steps to fix the twitching."
+ "Lazy-init for now for smooth transition -- want to convert this back to direct-var access after a few months."
+ 	^ movements ifNil: [ self initializeMovements ]!

Item was changed:
  ----- Method: ProportionalSplitterMorph>>repositionBy: (in category 'layout') -----
  repositionBy: delta
  	| selfTop selfBottom selfLeft selfRight |
  	leftOrTop do:
  		[ : each | | firstRight firstBottom |
  		firstRight := each layoutFrame rightOffset ifNil: [ 0 ].
  		firstBottom := each layoutFrame bottomOffset ifNil: [ 0 ].
  		each layoutFrame rightOffset: firstRight + delta x.
  		each layoutFrame bottomOffset: firstBottom + delta y ].
  	rightOrBottom do:
  		[ : each | | secondLeft secondTop |
  		secondLeft := each layoutFrame leftOffset ifNil: [ 0 ].
  		secondTop := each layoutFrame topOffset ifNil: [ 0 ].
  		each layoutFrame leftOffset: secondLeft + delta x.
  		each layoutFrame topOffset: secondTop + delta y ].
  	selfTop := self layoutFrame topOffset ifNil: [ 0 ].
  	selfBottom := self layoutFrame bottomOffset ifNil: [ 0 ].
  	selfLeft := self layoutFrame leftOffset ifNil: [ 0 ].
  	selfRight := self layoutFrame rightOffset ifNil: [ 0 ].
  	self layoutFrame
  		 topOffset: selfTop + delta y ;
  		 bottomOffset: selfBottom + delta y ;
  		 leftOffset: selfLeft + delta x ;
  		 rightOffset: selfRight + delta x.
+ 	self owner layoutChanged.
+ 	self movements removeFirst; add: (splitsTopAndBottom ifTrue: [ delta y sign ] ifFalse: [ delta x sign ])!
- 	self owner layoutChanged!

Item was changed:
  ----- Method: ProportionalSplitterMorph>>stepTime (in category 'events') -----
  stepTime
- 	| pause |
  	"When a splitter finds itself in the right place, let it rest for about 3 seconds to avoid performance impacts of constant, rapid stepping."
+ 	| pause |
  	pause := (2900 to: 3100) atRandom "to discourage any patternistic emergence".
+ 	^ ({#(1 -1 1 ).  #(-1 1 -1 )} includes: self movements asArray)
+ 		ifTrue: [ pause "don't twitch" ]
- 	^ splitsTopAndBottom
- 		ifTrue:
- 			[ self topBottomCorrection isZero
- 				ifTrue: [ pause ]
- 				ifFalse: [ 0 ] ]
  		ifFalse:
+ 			[ splitsTopAndBottom
+ 				ifTrue:
+ 					[ self topBottomCorrection isZero
+ 						ifTrue: [ pause ]
+ 						ifFalse: [ 0 ] ]
+ 				ifFalse:
+ 					[ self leftRightImbalance abs > 1
+ 						ifTrue: [ ">1 rather than 0 to discourage one-off twitching"
+ 							0 ]
+ 						ifFalse: [ pause ] ] ]!
- 			[ self leftRightImbalance abs > 1 ">1 rather than 0 to discourage one-off twitching"
- 				ifTrue: [ 0 ]
- 				ifFalse: [ pause ] ]!