[UX] Flat white tool cursors are hard to see while editing orange objects (Redmine #1956)

Usability problem.

When using editing tools the cursor changes shape to current tool/mode representation. Problem is that they are white without any border which is a problem when the background is light. Most of the time background is light, orange or more-light orange, which makes them hard to see even on good monitor.

Example in attached files.

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Posted by ~alextee in ~alextee/zrythm-feature#144