Show breakpoint hint even if there are other line decorations

[joyceerhl]

For #179725

This allows easy setting of breakpoints even if the current line already has a non-breakpoint decoration.

breakpoint-hint.mp4

One potential issue with this change is that it will cause the margin to resize if hovering on a line which already has a non-breakpoint decoration, which would cause a lot of visual flickering. We could address this by rendering a sentinel breakpoint to reserve the second lane for debug, which avoids the flickering at the expense of extra margin space even when the decoration has yet to be rendered. Another approach could be to debounce the margin resizing, which would reduce flickering at the expense of potential degraded performance.

[connor4312]

I'm not sure how I feel about this. Changing the layout of things on hover has accessibility concerns and also feels pretty disruptive. At least I think this should have a setting.

I wonder about an alternative:

• For non-clickable decorations (i.e. decorations from extensions) hovering the decoration replaces it with the breakpoint symbol
• For clickable decorations, the user has to right click on the gutter in order to set a breakpoint (same as the last stable)

[joyceerhl]

For non-clickable decorations (i.e. decorations from extensions) hovering the decoration replaces it with the breakpoint symbol

This seems reasonable, is the idea then that when you click to set the breakpoint, the second lane appears? If so I think this behavior is best controlled by the glyph margin rather than in the breakpoint contribution to avoid duplicating the logic for which lane to render the breakpoint in.

[connor4312]

is the idea then that when you click to set the breakpoint, the second lane appears?

Yea, I think so

[joyceerhl]

👍 I'll revisit the problem of how to show breakpoint hints when there are already non-breakpoint decorations after we have a notion of clickable decorations (glyph widgets).