diff --git a/sumorobot.js b/sumorobot.js
index 3841ea3..e50669f 100755
--- a/sumorobot.js
+++ b/sumorobot.js
@@ -280,8 +280,14 @@ window.onload = function() {
     /* resume the blocks */
     Blockly.Xml.domToWorkspace(xml, workspace);
 
-    /* disable right click on Blockly workspace */
+    /* when mouse click occures on Blockly workspace */
     Blockly.utils.isRightButton = function(e) {
+        /* if control_if block is used */
+        if (controlBlockId != "") {
+            /* close the control_if block mutator */
+            workspace.getBlockById(controlBlockId).mutator.setVisible(false);
+        }
+        /* disable right click on Blockly workspace */
         return false;
     };