horizontal scrollbar appears just for a moment then disappears - gwt

Question

I am using UiBinder and a DockLayoutPanel as shown below. I am adding a custom CellTable to the ScrollPanel named "contentPanel".
When the CellTable is created for the first time, a horizonal scrollbar appears (along with the cellTableLoading.gif). Once the CellTable is finishing loading the horizontal scrollbar disappears.
How can I prevent the horizontal scrollbar from appearing in the first place?
I'd be happy to provide any other info that will help troubleshoot the problem. Many thanks!
<g:DockLayoutPanel unit='PX' styleName="{style.wrap}">
<g:north size='180'>
<g:HTMLPanel styleName='{style.header}'>
<g:Hyperlink ui:field="logoutLink" styleName="{style.login}"/>
</g:HTMLPanel>
</g:north>
<g:south size="70">
<g:HTMLPanel styleName="{style.footer}">
<g:Label>© Copyright by</g:Label>
</g:HTMLPanel>
</g:south>
<g:center>
<g:HTMLPanel styleName='{style.content}'>
<g:SimplePanel styleName='{style.left}' ui:field="navigationPanel" />
<g:ScrollPanel styleName='{style.right}' ui:field='contentPanel' />
<div style="clear: both;" ></div>
</g:HTMLPanel>
</g:center>

Answer 1

Impossible to tell why it happens without seeing the markup that's being generated and your CSS styles, but to turn off the scrollbars temporarily you can do the following:
// Before you load your table
contentPanel.getElement().getStyle().setOverflow(Overflow.HIDDEN);
// load your table
// ....
// after table is loaded
contentPanel.getElement().getStyle().setOverflow(Overflow.AUTO);
As a side note, you should also implement the panel inside <g:center> as a LayoutPanel instead of floated divs. It will give you a much more predictable layout:
<g:center>
<g:LayoutPanel styleName='{style.content}'>
<g:layer left="0" width="200px">
<g:SimplePanel styleName='{style.left}' ui:field="navigationPanel" />
</g:layer>
<g:layer right="0" left="200px">
<g:ScrollPanel styleName='{style.right}' ui:field='contentPanel' />
</g:layer>
</g:LayoutPanel>
</g:center>
You would also, obviously need to remove any box model related styles from .left and .right, like width and float.