This is similar to #353026

The widget explorer closes when focus is lost.  This is likely the expected behavior with click to focus, but with focus follows mouse, it usually means that the explorer closes before there's a chance to get your mouse into it.  Either you have to be on a desktop with no windows visible, or quickly move your mouse to the location where the explorer will be; otherwise, if the pointer passes over a window (focusing it due to focus follows mouse), the explorer is closed.

I think that when focus follows mouse is enabled, the widget explorer should not close when focus changes.

Reproducible: Always

Steps to Reproduce:
1. Enable focus follows mouse
2. Open some windows
3. Select “Add Widgets” on a panel or the desktop
4. Attempt to move the mouse to the widget explorer, being sure to pass through some windows while doing so.

Actual Results:  
The widget explorer closes as soon as focus changes.

Expected Results:  
The widget explorer stays open until it is explicitly closed.