source/blender/editors/include/ED_sequencer.h

@@ -19,7 +19,13 @@ struct bContext;
 void ED_sequencer_select_sequence_single(struct Scene *scene,
                                          struct Sequence *seq,
                                          bool deselect_all);
-void ED_sequencer_deselect_all(struct Scene *scene);
+/**
+ * Iterates over a scene's sequences and deselects all of them.
+ *
+ * \param scene: scene containing sequences to be deselected.
+ * \return true if any sequences were deselected; false otherwise.
+ */
+bool ED_sequencer_deselect_all(struct Scene *scene);
 
 bool ED_space_sequencer_maskedit_mask_poll(struct bContext *C);
 bool ED_space_sequencer_check_show_maskedit(struct SpaceSeq *sseq, struct Scene *scene);

source/blender/editors/space_sequencer/sequencer_edit.c

@@ -2492,17 +2492,22 @@ void SEQUENCER_OT_copy(wmOperatorType *ot)
 /** \name Paste Operator
  * \{ */
 
-void ED_sequencer_deselect_all(Scene *scene)
+bool ED_sequencer_deselect_all(Scene *scene)
 {
   Editing *ed = SEQ_editing_get(scene);
+  bool changed = false;
 
   if (ed == NULL) {
-    return;
+    return changed;
   }
 
   LISTBASE_FOREACH (Sequence *, seq, SEQ_active_seqbase_get(ed)) {
+    if (seq->flag & SEQ_ALLSEL) {
       seq->flag &= ~SEQ_ALLSEL;
+      changed = true;
     }
+  }
+  return changed;
 }
 
 static void sequencer_paste_animation(bContext *C)

source/blender/editors/space_sequencer/sequencer_select.c

@@ -974,8 +974,7 @@ static int sequencer_select_exec(bContext *C, wmOperator *op)
 
   /* Deselect everything */
   if (deselect_all || (seq && (extend == false && deselect == false && toggle == false))) {
-    ED_sequencer_deselect_all(scene);
+    changed |= ED_sequencer_deselect_all(scene);
-    changed = true;
   }
 
   /* Nothing to select, but strips could be deselected. */