the meaning of cells in this table:
- nothing: that constraint for that plasmoid has not been checked yet
- T: the plasmoid cannot satisfy this constraint and X-Plasma-Requires-<contraint>=true has been set in the .desktop file.
- F: the plasmoid satisfies this constraint and X-Plasma-Requires-<contraint>=false has been set in the .desktop file.
- O: it has made optional in the code using isAllowed, and X-Plasma-Requires-<contraint>=false has been set in the .desktop file.
oh bloody hell. the .desktop file has no way to mark optional, which is bad for scripts, because if they say false they may never get it at all. FIXME I think I need to change from a bool to an enum or something, and I hope it's not too late.