A standard folder icon as an internal icon

[highend]

E.g. ":folder"

I often want to display folders e.g. in a popupmenu / popupnestedmenu and a normal internal folder icon would make the whole thing a lot more smoother
instead of the necessity to provide a folder icon as a .png / .ico file...

":showfolders" isn't really a valid option here

[admin]

I will add this pseudo extension for folders in this context: *.<DIR>