In an app I'm starting, I have a horizontal splitview (NSSPlitview) and in the top half of that I have another splitview (this time vertical) to make a 3-pane window. Two panes at the top, one across the bottom. A little bit like, say, FCP.
Both NSSplitViews are using the thin-divider style.
The issue is, if I resize the app window, or move any of the dividers, then the splitviews re-size correctly, but the original dividers stay on screen, in the original positions! Nothing I do after that will remove the original dividing lines.
Here's a screenshot at app launch
and here's a screenshot after resizing the app window.
How do I remove these artefacts?
