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, 4 insertions, 0 deletions

diff --git a/source/blender/editors/include/ED_screen.h b/source/blender/editors/include/ED_screen.h
index 2291e70fa4d..97653286f28 100644
--- a/source/blender/editors/include/ED_screen.h
+++ b/source/blender/editors/include/ED_screen.h
@@ -318,6 +318,10 @@ void ED_region_cache_draw_background(const struct ARegion *ar);
 void ED_region_cache_draw_curfra_label(const int framenr, const float x, const float y);
 void ED_region_cache_draw_cached_segments(const struct ARegion *ar, const int num_segments, const int *points, const int sfra, const int efra);
 
+/* interface_region_hud.c */
+struct ARegionType *ED_area_type_hud(int space_type);
+void ED_area_type_hud_ensure(struct bContext *C, struct ScrArea *sa);
+
 /* default keymaps, bitflags */
 #define ED_KEYMAP_UI        1
 #define ED_KEYMAP_VIEW2D    2