title: GXT grid header width unaligned with content if scrollbar visible
body: <p>I have a display problem with my gxt grids (GXT 2.3.1, <code>com.extjs.gxt.ui.client.widget.grid</code>). It is only visible if horizontal and vertical scrollbars are present: As you can see on the screenshot, the header is missing a space on the right side (above the scrollbar). This causes that header to be unaligned with the columns. The issue isn't easy to reproduce and occurs quite randomly, sometime after the grid has been resized.</p>
  
  <p>This is also reproducible with GXT3: <a href="https://www.sencha.com/examples/#ExamplePlace:remotefiltergrid" rel="nofollow noreferrer">https://www.sencha.com/examples/#ExamplePlace:remotefiltergrid</a> (you have to change the grid and column size to reproduce)</p>
  
  <p><a href="https://i.stack.imgur.com/GbY3V.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/GbY3V.png" alt="enter image description here"></a></p>