Marcel Taeumel uploaded a new version of ST80 to project The Trunk:
http://source.squeak.org/trunk/ST80-mt.251.mcz

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

Name: ST80-mt.251
Author: mt
Time: 15 April 2020, 5:53:42.145699 pm
UUID: 07f97eb2-f0c8-df4c-9f7b-fa6225418264
Ancestors: ST80-mt.250

For MVC projects, fixes high CPU load during empty world and while scrolling lists.

=============== Diff against ST80-mt.250 ===============

Item was changed:
  ----- Method: Controller>>controlLoop (in category 'basic control sequence') -----
  controlLoop 
  	"Sent by Controller|startUp as part of the standard control sequence. 
  	Controller|controlLoop sends the message Controller|isControlActive to test 
  	for loop termination. As long as true is returned, the loop continues. 
  	When false is returned, the loop ends. Each time through the loop, the 
  	message Controller|controlActivity is sent."
  
+ 	[self interActivityPause. self isControlActive] whileTrue: [
+ 		self controlActivity. Processor yield]!
- 	[self isControlActive] whileTrue: [
- 		self interActivityPause. self controlActivity. Processor yield]!

Item was changed:
  ----- Method: ScrollController>>scrollAbsolute (in category 'private') -----
  scrollAbsolute
  	| markerOutline oldY markerForm |
  	self changeCursor: Cursor rightArrow.
  
  	oldY := -1.
  	sensor anyButtonPressed ifTrue: 
  	  [markerOutline := marker deepCopy.
  	  markerForm := Form fromDisplay: marker.
  	  Display fill: marker fillColor: scrollBar insideColor.
  	  Display border: markerOutline width: 1 fillColor: Color gray.
  	  markerForm 
  		follow: 
  			[oldY ~= sensor cursorPoint y
  				ifTrue: 
  					[oldY := sensor cursorPoint y.
  					marker := marker translateBy: 
  					  0 @ ((oldY - marker center y 
  						min: scrollBar inside bottom - marker bottom) 
  						max: scrollBar inside top - marker top).
  					self scrollView].
  				marker origin] 
+ 		while: [
+ 			self interActivityPause.
+ 			sensor anyButtonPressed].
- 		while: [sensor anyButtonPressed].
  
  	  Display fill: markerOutline fillColor: scrollBar insideColor.
  	  self moveMarker]!