some commentd added

src/callback.c

@@ -4236,6 +4236,10 @@ int rstate; /* (reduced state, without ShiftMask) */
        /* intuitive interface: directly drag elements */
        if(sel.type && xctx->intuitive_interface && xctx->lastsel >= 1 &&
           !xctx->shape_point_selected) {
+         /* enable_stretch (from TCL variable) reverses command if enabled:
+          * - move --> stretch move
+          * - stretch move (with ctrl key) --> move
+          */
          int stretch = (state & ControlMask ? 1 : 0) ^ enable_stretch;
          xctx->drag_elements = 1;
          /* select attached nets depending on ControlMask and enable_stretch */
@@ -4250,7 +4254,7 @@ int rstate; /* (reduced state, without ShiftMask) */
          }
          /* dragging away an object with Shift pressed is a copy (duplicate object) */
          else if(state & ShiftMask) copy_objects(START);
-         /* else it is a move */
+         /* else it is a normal move */
          else move_objects(START,0,0,0);
        }