Change all action callbacks so they can be invoked by a GAction:
- add GimpActionCallback typedef:
void (* cb) (GimpAction*, GVariant*, gpointer)
- change all action callbacks to the GimpActionCallback signature
- add "gimp-activate" and "gimp-change-state" signals to GimpAction,
with the same signature as the resp. GAction signals
- remove all other custom action signals and only use the new
GimpAction signals
- pass around appropriate GVariants containing booleans, int32,
strings
- badly hack around to force a GimpProcedure pointer into a
uint64 variant
- remove all G_CALLBACK() casts from all action callbacks,
they all have the same signature now
(cherry picked from commit 3b6b3fc189)
Have "Save" and "Restore" buttons in both the tool preset list/grid
and the tool preset editor. The save button stores the active tool's
options in the preset, if possible.
In order to make things more obvious here. Before, a tool preset could
only be rstored from the list by selecting it, which only worked if
another preset was active before. Now the selected preset can easily
be restored again.
