Editor tree view GUI issue

I’m working as Manuscript/Part 1/Chapter 1/Scene 1.
When I click on Part 1 in the binder I get a tree view of chapters in the top editor.

The issue I’m seeing is that the tree’s first level +/- (expand/collapse) icons are only partially accessible. Only the right half of the icon works. Positioning over the left half triggers the separator drag icon (2 vertical bars with a double headed horizontal arrow) and that takes the mouse actions.

It’s very annoying. I have to be very very accurate in placing the mouse pointer over the right half of the icon to click it so it works.

I think there needs to be more empty space along the left edge of the editor so that the entirety of the +/- icons are usable without triggering the border drag icon.

Note: When I first spotted this the border drag icon did not appear but the left half of the +/- icons simply did not work. That happened several times but since then I’ve not been successful in reproducing it. So there may be another issue here.