Undo: unified undo system w/ linear history

- Use a single undo history for all operations.
- UndoType's are registered and poll the context to check if they
  should be used when performing an undo push.
- Mode switching is used to ensure the state is correct before
  undo data is restored.
- Some undo types accumulate changes (image & text editing)
  others store the state multiple times (with de-duplication).
  This is supported by checking UndoStack.mode `ACCUMULATE` / `STORE`.
- Each undo step stores ID datablocks they use with utilities to help
  manage restoring correct ID's.
  Needed since global undo is now mixed with other modes undo.
- Currently performs each undo step when going up/down history
  Previously this wasn't done, making history fail in some cases.
  This can be optimized to skip some combinations of undo steps.

grease-pencil is an exception which has not been updated
since it integrates undo into the draw-session.

See D3113

1 files changed, 7 insertions, 1 deletions

diff --git a/source/blender/windowmanager/intern/wm.c b/source/blender/windowmanager/intern/wm.c
index 9e877a83b3e..8be7555b34a 100644
--- a/source/blender/windowmanager/intern/wm.c
+++ b/source/blender/windowmanager/intern/wm.c
@@ -61,6 +61,7 @@
 #include "wm.h"
 
 #include "ED_screen.h"
+#include "BKE_undo_system.h"
 
 #ifdef WITH_PYTHON
 #include "BPY_extern.h"
@@ -485,7 +486,12 @@ void wm_close_and_free(bContext *C, wmWindowManager *wm)
 	WM_drag_free_list(&wm->drags);
 	
 	wm_reports_free(wm);
-	
+
+	if (wm->undo_stack) {
+		BKE_undosys_stack_destroy(wm->undo_stack);
+		wm->undo_stack = NULL;
+	}
+
 	if (C && CTX_wm_manager(C) == wm) CTX_wm_manager_set(C, NULL);
 }