VSE: Clarify why frame range is drawn differently than in other editors.

source/blender/editors/space_sequencer/sequencer_edit.c

@@ -3277,6 +3277,9 @@ static int sequencer_set_range_to_strips_exec(bContext *C, wmOperator *op)
     if (seq->flag & SELECT) {
       selected = true;
       sfra = min_ii(sfra, SEQ_time_left_handle_frame_get(scene, seq));
+      /* Offset of -1 is needed because in VSE every frame has width. Range from 1 to 1 is drawn
+       * as range 1 to 2, because 1 frame long strip starts at frame 1 and ends at frame 2.
+       * See #106480. */
       efra = max_ii(efra, SEQ_time_right_handle_frame_get(scene, seq) - 1);
     }
   }