This only helps to maintain proper includes in app/ and shouldn't
affect plug-ins at all, because these are supposed to only include the
main headers from libgimp/ since the beginning of time.
The gimpfootypes.h files do not have these guards, so we can continue
to maintain app/'s include policy that is very likely to error out if
wrong things are included.
to allow having unit combos without "pixels". Adapt GimpUnitComboBox
to not assume that the unit is equal to the index in the store and
enable "menu_has_pixels" in GimpSizeEntry again.
Michael Natterer