Visual glitch with static line separators (macOS) - upstream issue

[facelessuser]

The current version(s) of wxPython (or maybe it is wxWidgets - the underlying library) has a bug with static line separators on specifically macOS. Horizontal lines don't render and vertical lines render poorly. This issue is to remain open until it is fixed so we can remove the workaround at some future time.

How things used to look.

How things look now.

We will be hiding vertical line separators until this is fixed. It will at least match the horizontal line glitch.