> > I would be very unhappy if changing the layer opacity from 100% to 50%
> > would eat up a dozen or more undo-steps since each value_changed signal
> > from the slider triggers an undo which causes another undo-step fall
> > off the end of the undo queue.
> Oh, sure - that's clearly a bad idea.
> I was thinking of only pushing the undo when you release the slider.
> That doesn't help those using the keyboard to nudge the slider though.
> This could be done by pushing a group start on mouse down, and closing
> it on mouse up, for example.
Gtk+ is already prepared for that. Changing line 420 in
gtk_range_set_update_policy (GTK_RANGE (slider), GTK_UPDATE_DELAYED);
should do the trick without any fiddling with events.
I still believe that it is a bad idea to waste undo steps for operations
that don't save any shadow tiles. How hard would it be to change the
undo system so that the number of undo steps is calculated only from
"real" undos? What about the idea of merging consecutive changes to the
layer attributes into one?