title: ExtJS mask panel while actions are made
body: <p>I have an Ext west panel from my viewport and I have a handler on a button that first removes all elements from west then ads another element, then does a doLayout(). So there are 3 things this function does on the click of the button. I would like to add a mask to the west panel when the button is clicked and unmask after all 3 tasks are completed.</p>
  
  <p>Here is the panel:</p>
  
  <pre><code>{
                  region: 'west',
                  id: 'west-panel',
                  title: 'West',
                  split: true,
                  width: 200,
                  minSize: 175,
                  maxSize: 400,
                  collapsible: true,
                  margins: '0 0 0 5',
                  layout: 'fit'
                  items: [leftMenu]
              }
  </code></pre>
  
  <p>And this is how I do the tasks:</p>
  
  <pre><code>west.removeAll();
  west.add(indexHeaderPanel);
  west.doLayout();
  </code></pre>
  
  <p>Is this possible ? I will give more informations if asked. Thank you.</p>