Bug 859490 - When switching selection modes, hide all carets. r=bbondy

browser/metro/base/content/helperui/SelectionHelperUI.js

@@ -351,6 +351,8 @@ var SelectionHelperUI = {
     if (!this.isActive) {
       this._init(aBrowser);
       this._setupDebugOptions();
+    } else {
+      this._hideMonocles();
     }
 
     this._lastPoint = { xPos: aX, yPos: aY };