Weird problem. I have a bunch of my own-style of actors in sub-panels. When the sub-panels are 3 levels deep their splitters appear to be slightly visible? I have colored the vertical and horizontal splitters the same color as the background.
Anyone else have this problem?
Top-Level VI (See the faint vertical and horizontal lines from splitter)
Same VI one less level deep, no lines from splitters visible at all..
There is a right-click setting on subpanels, I think called "Make panel transparent" or something similar. Make sure this is off on your top subpanel. I suspect it is on, and your top vi has a slightly lighter panel colour.