The normal quick filter is activated, even if before going to 1 pane, the filter was inverted (see "Inverse quick filter" option).
LE: If the quick filter is empty, you won't get this behaviour.
Besides, as for quick filter or see only selected files (CTRL+S), I really would like to have the option to have the background colored with I activate "toggle folder visibility" (hide folders in pane, keep only files).
Very often I forget I have hidden the folders, and I have a few moments of astonishment not knowing where they're gone...
I am aware this is a feature request, but I'll leave it here
