I'm not sure if it's a bug, if it's a feature or if I am doing something wrong:
I have a collapsible panel in the north-region of the viewport.
The panel has got a header with some tools.
When the panel got collapsed and floated afterwards, a second panel becomes apparent. I think that this looks very curious.
Furthermore, when the panel gets collapsed again the tools are not shown on the panels header any longer.
This is an ExtJS bug and I would report it in the bug forum.
Run the fiddle. Note that there are 2 icons: collapse refresh
Collaps the panel. Note that there is 1 icon: collapse
Now, instead of clicking on the expand icon, click to the left where the collapse icon was before the collapse
It behaves even worse if the panel is north but you have to go into the web inspector to get rid of the jsfiddle "result" button which prevents clicking the icons.