Marcel Taeumel uploaded a new version of Graphics to project The Trunk:
http://source.squeak.org/trunk/Graphics-mt.519.mcz

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

Name: Graphics-mt.519
Author: mt
Time: 3 June 2022, 11:46:00.379122 am
UUID: 617a1b80-ce28-3146-8ddd-1544e6042cc8
Ancestors: Graphics-mt.518

To avoid graphics glitches when drawing text selections, adjust #lineHeight instead of #bottomMargin to realize #lineSpacing during text composition.

=============== Diff against Graphics-mt.518 ===============

Item was changed:
  ----- Method: CompositionScanner>>composeFrom:inRectangle:firstLine:leftSide:rightSide: (in category 'scanning') -----
  composeFrom: startIndex inRectangle: lineRectangle
  	firstLine: firstLine leftSide: leftSide rightSide: rightSide
  	"Answer an instance of TextLineInterval that represents the next line in the paragraph."
  	| runLength stopCondition lineSpacing |
  	"Set up margins"
  	leftMargin := lineRectangle left.
  	leftSide ifTrue: [leftMargin := leftMargin +
  						(firstLine ifTrue: [textStyle firstIndent]
  								ifFalse: [textStyle restIndent])].
  	destX := spaceX := leftMargin.
  	rightMargin := lineRectangle right.
  	rightSide ifTrue: [rightMargin := rightMargin - textStyle rightIndent].
  	lastIndex := startIndex.	"scanning sets last index"
  	destY := lineRectangle top.
  	lineHeight := baseline := 0. "Will be increased by setFont"
  	lineGap := lineGapSlice := -9999. "Will be increased by setFont; allow negative to show all effects of a custom #extraGap value. See TTFontDescription."
  	topMargin := bottomMargin := 0.
  	line := (TextLine start: lastIndex stop: 0 internalSpaces: 0 paddingWidth: 0)
  				rectangle: lineRectangle.
  	self setStopConditions.	"also sets font"
  	runLength := text runLengthFor: startIndex.
  	runStopIndex := (lastIndex := startIndex) + (runLength - 1).
  	nextIndexAfterLineBreak := spaceCount := 0.
  	lastBreakIsNotASpace := false.
  	self handleIndentation.
  	leftMargin := destX.
  	line leftMargin: leftMargin.
  
  	[stopCondition := self scanCharactersFrom: lastIndex to: runStopIndex
  		in: text string rightX: rightMargin.
  	"See setStopConditions for stopping conditions for composing."
  	self perform: stopCondition] whileFalse.
  
  	lineHeight := lineHeight + lineGap.
  	baseline := baseline + lineGapSlice.
  	
+ 	(lineSpacing := textStyle lineSpacing) = 0.0 ifFalse: [
+ 		"Modify lineHeight to realize lineSpacing instead of bottomMargin to avoid
+ 		rendering glitches for lineSpacing values < 0.0."
+ 		lineHeight := lineHeight + (lineSpacing * lineHeight) truncated.
+ 		"ALT: bottomMargin := bottomMargin + (lineSpacing * lineHeight) truncated"].
- 	"TODO: Allow special characters or text attributes to accumulate extra top or bottom margin."
- 	(lineSpacing := textStyle lineSpacing) = 0.0
- 		ifFalse: [bottomMargin := bottomMargin + (lineSpacing * lineHeight) truncated].
  
  	line lineHeight: lineHeight baseline: baseline.
+ 	"TODO: Allow special characters or text attributes to accumulate extra top or bottom margin."
  	line topMargin: topMargin bottomMargin: bottomMargin.
  	^ line!