Bug 357191

Edges of an already created panel are wrongly replaced to match the edges of a newly created panel. Having more than one panel always causes visual inconsistencies.

My current panel setup consists of a maximized bottom panel and an unmaximized panel on the right side of the screen.
If I first create the maximized bottom panel, it is displayed perfectly. The moment I add a second panel, the edges of the preexisting bottom panel change to match that of the new panel. This means the bottom panel has visible left and top-left corners even though it is maximized and, as such, should only have a top edge. Removing the left-panel fixes it immediately. Similarly, putting the second panel on the left side of the screen causes right and top-right borders to appear on the bottom panel, and putting in on the top hides all borders on the bottom panel, including the top border.
If I instead create the maximized bottom panel second, the first panel ends up having only a top-border.

This can easily be visualized by using with the attached panel-background.svg file.

Reproducible: Always

Steps to Reproduce:
1. Have an existing panel (A)
2. Add a second panel (B)

Actual Results:  
Panel B's edges replace Panel A's

Expected Results:  
Each panel keeps its own edges.