small mark fix

src/ui/view/MyCanvas.java

@@ -405,6 +405,7 @@ public class MyCanvas extends JPanel implements MouseListener, MouseMotionListen
 
 		// Mark Objects
 		if (doMark) {
+			TempSelected.clear();
 			for (CpsObject cps : model.getObjectsOnCanvas()) {
 				int x1 = sx, x2 = x, y1 = sy, y2 = y;