Describe the bug
In the Cairo Settings,I have "Enable notification area" checked. I wanted to drag some icons from the collapsible region to the pinned region. Whenever I would click and drag and icon, either the icon would fail to move at all, or the wrong icon would be moved. It doesn't always happen.

Frequently I was also not allowed to drop the icon in the other area at all (the cursor would become a circle with slash symbol).

Steps to reproduce

1. Open Cairo Settings -> Menu Bar. Ensure "Enable notification area" is checked.
2. Click on one of the icons in the collapsible area and drag it to the pinned area (or vice versa).

Expected behavior
The icon should disappear from the region it was dragged from, and appear in the region it was dragged to. It should be possible to drop the icon anywhere in the area I want it to appear. Other icons that I wasn't interacting with should not move.

System information:

• Windows version: Windows 10 21H1, OS Build 19043.1526
• Cairo version: 0.4.174.64607
• 32-bit or 64-bit: 64-bit
• In Cairo Settings > Advanced, is Cairo set as shell?: No

Additional context
I did move some system icons (network and sound) back and forth in my efforts. I'm not sure if this was part of the problem.