 
           when 90 then if ctrlKeyPressed
             @undo()
+            event.preventDefault()
         
         # If we manipulated the root tree, redraw.
         if event.keyCode in [13, 38, 40, 8] then @redraw()
         
         # If we caught the keypress, prevent default.
-        if event.keyCode in [13, 38, 40, 8, 37, 90] then event.preventDefault()
+        if event.keyCode in [13, 38, 40, 8, 37] then event.preventDefault()
 
       @el.addEventListener 'keyup', (event) =>
         switch event.keyCode

      @hiddenInput.addEventListener 'blur', (event) =>
        # If we have actually blurred (as opposed to simply unfocused the browser window)
        if event.target isnt document.activeElement then setTextInputFocus null
      
      # Bind keyboard shortcut events to the document
      

            # put the cursor into the input that changed.
            when 'socketTextChange'
              socketStart = @tree.getTokenAtLocation operation.location
              socketStart.socket.content()?.remove()
              socketStart.insert new model.TextToken operation.before
              
              setTextInputFocusRaw socketStart.socket
