title: GWT Datagrid does not show data , but contains it
body: <p>I'm trying to convert a <code>cellTable</code> into a<code>datagrid</code>, because I want to add a search handler later and therefor I need fixed column headers. At the moment I extend the <code>celltable</code>/<code>datagrid</code> class and put the widget into a <code>simplelayoutpanel</code> and add this to my <code>tabpanel</code>. </p>
  
  <p>If I use the <code>celltable</code>, all works fine and the data shows up. If I change the type of the class to <code>datagrid</code>, the data shows sometimes up (The column names are always there). To add something to the table I used <code>setRowData</code> or a <code>dataProvider</code>. If I set breakpoints to delay the loading of the table content, the table does sometimes contain data. If I later call the redraw method for the table, the table shows the correct information. But the table should load automatically the content. At other "positions" of my project I used the datagrid also and it worked in <code>Dialogboxes</code>.</p>
  
  <p>I think there must be a bug with the drawing of the items, because if I call <code>.getRowCount</code> on the table or the deprecated <code>.getDisplayedItems</code>, it returns me the correct number of items which should be in the table. Also if I add a selection model to the table and select a item, the item contains valid data.</p>