@graesslin pointed out in D10314 that F11 is the standard shortcut for "Enter/Exit full screen" in most apps, including many KDE apps. But Dolphin currently uses this for "Show/hide Information Panel". And we just added the same shortcut to KIO's Open/Save dialogs for consistency with Dolphin.
We should consider changing this--and in the process all of the other panel shortcuts for consistency. Rough initial proposal:
Places panel: ctrl+alt+p
Folders panel: ctrl+alt+f
Information Panel: ctrl+alt+i
Terminal panel: ctrl+alt+t
If we decided to do it, changes will also need to be made to a few KIO filewidgets, as shown in D10314