Show breakpoint widget on Alt+click in gutter

[yogeshwaran-c]

Summary

• Adds Alt+click handling in the editor gutter to quickly add or edit conditional breakpoints
• When Alt+clicking on a line without breakpoints, the breakpoint widget opens in conditional breakpoint mode
• When Alt+clicking on a line with existing breakpoints, the breakpoint widget opens for editing the first breakpoint

This makes it easier to add conditional breakpoints without going through the context menu, consistent with how Shift+click toggles breakpoint enable/disable and middle-click opens the breakpoint widget.

Test plan

• Alt+click on an empty gutter line: should open the breakpoint widget in conditional breakpoint mode
• Alt+click on a gutter line with an existing breakpoint: should open the breakpoint widget to edit the breakpoint
• Regular click on empty gutter line: should still add a breakpoint (no regression)
• Shift+click on existing breakpoint: should still toggle enable/disable (no regression)
• Middle-click behavior: should still work as before (no regression)

Fixes #203259

[Copilot]

Pull request overview

Adds an Alt+click interaction in the editor glyph margin to open the breakpoint widget, improving the workflow for adding conditional breakpoints and editing existing breakpoints directly from the gutter.

Changes:

• Handle Alt+click on an existing breakpoint to open the breakpoint widget for editing.
• Handle Alt+click on an empty gutter line to open the breakpoint widget preselected to “Conditional Breakpoint”.

Show a summary per file

File	Description
src/vs/workbench/contrib/debug/browser/breakpointEditorContribution.ts	Adds Alt+click mouse handling in the glyph margin to open the breakpoint widget in edit/conditional modes depending on whether breakpoints already exist on the line.

Copilot's findings

Comments suppressed due to low confidence (1)

src/vs/workbench/contrib/debug/browser/breakpointEditorContribution.ts:337

• Because the altKey check comes before middleButton, Alt+middle-click on an empty gutter line will now open the conditional breakpoint widget instead of honoring the configured debug.gutterMiddleClickAction. To avoid regressing middle-click behavior, consider either (1) checking middleButton first, or (2) requiring e.event.leftButton for the Alt+click path.

					if (e.event.altKey) {
						// Alt+click on empty gutter opens the breakpoint widget for adding a conditional breakpoint
						this.showBreakpointWidget(lineNumber, undefined, BreakpointWidgetContext.CONDITION);
					} else if (e.event.middleButton) {

• Files reviewed: 1/1 changed files
• Comments generated: 1

[roblourens]

Nice, thanks