UI: Initial persistent floating redo panel

This is the first step to moving redo out of the top-bar, see: T55039

- Support for floating panels in the ScrArea has been added.
- A new region type RGN_TYPE_HUD is used for floating settings input.
- Only one HUD should be visible at a time.
- Currently HUD regions are only visible
  for 3D view and image space types.
- There are currently some remaining glitches with hide/show
  that need further investigation.

1 files changed, 8 insertions, 0 deletions

diff --git a/source/blender/windowmanager/intern/wm_event_system.c b/source/blender/windowmanager/intern/wm_event_system.c
index ffef33d344a..ebf771c4745 100644
--- a/source/blender/windowmanager/intern/wm_event_system.c
+++ b/source/blender/windowmanager/intern/wm_event_system.c
@@ -873,6 +873,14 @@ static void wm_operator_finished(bContext *C, wmOperator *op, const bool repeat,
 
 			wm_operator_register(C, op);
 			WM_operator_region_active_win_set(C);
+
+			/* Show the redo panel. */
+			{
+				ScrArea *sa = CTX_wm_area(C);
+				if (sa) {
+					ED_area_type_hud_ensure(C, sa);
+				}
+			}
 		}
 		else {
 			WM_operator_free(op);