I noticed that some in themes the selection area was hardly visible. In some cases the theme had been converted from Sublime Text, which has a selection outline feature that Atom lacks.
Take for instance Rainbow
With some CSS trickery I was able to get some outlines working. It’s available in the package selection-outlines.
But CSS has its limitations. Ideally, the divs that make up the selection region should be replaced by an SVG shape or something, but that’s outside my skill level. Any ideas?
Edit: some further thoughts about why this is important/interesting:
An outline allows you to lower the contrast between the regular background and that of the selection. High contrast makes the selection stand out more, but reduces readability of the code inside that area.