Drivers UI (Part of T55145) - WIP first steps towards getting a floating driver settings panel

This commit adds a new menu entry - "Edit Driver" - the RMB menu that
will show a popover panel displaying the settings for the driver you
activated the menu item on. This shows the popover panel defined in
yesterday's commit (GRAPH_PT_drivers_popover).

It is possible to edit the driver settings from this panel now.
However, do be warned that the functionality presented is highly
WIP still. There are some unresolved issues, such as:
 - The popover disappears too easily on any mouse movements/clicks
   on anything, making the panel less useful right now than it should.

 - The layout still needs refining. Currently the layout that's there
   is a bit of a placeholder until we can play around with it a bit
   more to see/feel what feels good/right or what is too much.

 - The "Open Drivers Editor" on the bottom of the panel doesn't work.
   There are some tricky context tricky things that need to happen here
   to make that case work, since the operator button won't have the necessary
   context info.

1 files changed, 1 insertions, 0 deletions

diff --git a/source/blender/editors/animation/anim_intern.h b/source/blender/editors/animation/anim_intern.h
index c571da1ba74..824c1d58f44 100644
--- a/source/blender/editors/animation/anim_intern.h
+++ b/source/blender/editors/animation/anim_intern.h
@@ -79,6 +79,7 @@ void ANIM_OT_keying_set_active_set(struct wmOperatorType *ot);
 /* Driver management operators for UI buttons (RMB menu) */
 void ANIM_OT_driver_button_add(struct wmOperatorType *ot);
 void ANIM_OT_driver_button_remove(struct wmOperatorType *ot);
+void ANIM_OT_driver_button_edit(struct wmOperatorType *ot);
 void ANIM_OT_copy_driver_button(struct wmOperatorType *ot);
 void ANIM_OT_paste_driver_button(struct wmOperatorType *ot);