widget: ensure editor does not trim trailing whitespace

This commit makes the editor widget suppress the trimming of trailing whitespace
so that the spaces can be selected intuitively.

Signed-off-by: Chris Waldon <christopher.waldon.dev@gmail.com>

widget/editor.go

@@ -610,6 +610,7 @@ func (e *Editor) initBuffer() {
 	e.text.SingleLine = e.SingleLine
 	e.text.Mask = e.Mask
 	e.text.WrapPolicy = e.WrapPolicy
+	e.text.DisableSpaceTrim = true
 }
 
 // Update the state of the editor in response to input events. Update consumes editor

widget/text.go

@@ -61,6 +61,9 @@ type textView struct {
 	Truncator string
 	// WrapPolicy configures how displayed text will be broken into lines.
 	WrapPolicy text.WrapPolicy
+	// DisableSpaceTrim configures whether trailing whitespace on a line will have its
+	// width zeroed. Set to true for editors, but false for non-editable text.
+	DisableSpaceTrim bool
 	// Mask replaces the visual display of each rune in the contents with the given rune.
 	// Newline characters are not masked. When non-zero, the unmasked contents
 	// are accessed by Len, Text, and SetText.
@@ -285,6 +288,10 @@ func (e *textView) Layout(gtx layout.Context, lt *text.Shaper, font font.Font, s
 		e.params.LineHeightScale = e.LineHeightScale
 		e.invalidate()
 	}
+	if e.DisableSpaceTrim != e.params.DisableSpaceTrim {
+		e.params.DisableSpaceTrim = e.DisableSpaceTrim
+		e.invalidate()
+	}
 
 	e.makeValid()