Looks like this should be added in the Effect.py superclass so that any active label effect would respond to it while processing events coming from the vtk window. The other option would be to add it as a global key binding on the mainwindow at the Qt level. The advantage of this would be that the slice view would not have to have focus for the option to work. We would have to be sure that a global binding on a single character would not cause problems when trying to use an entry (like renaming a volume).

also 'esc' does not work, so it is not possible to cancel active effect using keyboard

These should work as of revision 21875