Border entire line, regardless of word wrap

[hickford]

Depending on theme, the active line is highlighted with a background or border. Previously, when word wrap was enabled, the border did not surround the entire line. This was confusing because commands like "cut" and "copy" apply to the entire line.

Move top and bottom borders to surround the entire line. Remove left and right borders -- these obscured text.

Delete unused method "_shouldRenderOther".

Tested with various combinations of workbench.colorTheme, editor.wordWrap and editor.renderLineHighlight.

Fixes #36839
Fixes #214857

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Timeline:

• 2017: first bug renderLineHighlight should highlight logical line  #36839 with screenshots of both "background" and "border" themes
• 2023: fix for "background" themes only highlight whole line when word wrap enabled #198559
• 2024: second bug, specific to "border" themes lineHighlightBorder should frame all warped line #214857

[hickford]

With word wrap enabled, screenshots before and after:

[hickford]

Without word wrap enabled, screenshots before and after. There's a tiny 1 pixel difference on the left, which I think is an improvement.

[aiday-mar]

Hi thank you @hickford for doing this PR. I wonder if we should merge this PR. Perhaps users are used to seeing the box surround the active view line and not the active mode line, and I wonder if they will be confused if we start surrounding the model line instead.

[aiday-mar]

I have thought about this some more and I am not sure if we should implement this so it is the default behavior. The reasons for this are the following.

1. I have recently merged the feature which allows defining variable line heights in the editor, so a line can have a height of 30 and the one after can have a height of 50. The advantage of having the border surround the view line only and not the model line is that it allows the user to better grasp the exact height of the given view line (which can differ as explained). This is especially important when line numbers are not visible in the gutter.
2. I think screen reader users may well be relying on the active view line being highlighted when coding. If the whole model line is highlighted, it makes it could make it hard to distinguish where the cursor is located for screen reader users.

As such I suggest we add a setting to control this behavior which will control whether we surround the view line or the model line. I think the default should be the current behavior.

[aiday-mar]

As well as this I noticed you could simplify the code as follows:

renderData[lineIndex] = this._renderOne(ctx, lineNumber === firstLine, lineNumber === lastLine);

Also generally we try to keep changes to a minimum in PRs so as to minimize the risk of breaking existing behavior so I would suggest to remove the _shouldRenderOther method in a separate PR and to not modify the class names where possible. If you do modify a class name I think it would be useful to verify that this initial class name is not referenced elsewhere. I saw for example that current-line-exact was referenced in the file view.css so the class-name also needs to be changed there.