GWT data grid isn't presented

I'm trying to switch from CellTable to DataGrid. The actual change was very easy (APIs are the quite the same) - but I cannot get the grid to be visible without setting explicitly its width and height. In the CellTable it was enough to set width and height to 100% - and that is the behavior I want.

In my view I have two sections in HotrizontalPanel: one shows some tabs (buttons) and the other shows the grid. Each time a tab is clicked, the grid area is cleared and a new grid is created.

The view looks like this:

<ui:style>
     .expanded {
         width: 100%;
         height: 100%;
     }
 
     .simpleContainer {
         border-top: 5px solid #484848;
         border-bottom: 5px solid #484848;
     }
 </ui:style>
 
 <c:SimpleContainer addStyleNames="{style.simpleContainer} SimpleContainer">
     <g:HorizontalPanel>
         <g:HorizontalPanel ui:field="headersContainer"/>
         <g:FlowPanel ui:field="tablePanel" styleName="{style.expanded}"/>
     </g:HorizontalPanel>
 </c:SimpleContainer>
 

And this is the snap of HTML from the running application:

<div class="GKQJTVMDCNC-com-mycode-management-client-ui-panels-PropertiesPaneView_PropertiesPaneUiBinderImpl_GenCss_style-simpleContainer SimpleContainer" id="x-widget-21" style="width: 1730px; height: 126px; ">
 <table cellspacing="0" cellpadding="0">
     <tbody>
         <tr>
             <td align="left" style="vertical-align: top; ">....</td>
             <td align="left" style="vertical-align: top; ">
                 <div class="GKQJTVMDBNC-com-mycode-management-client-ui-panels-PropertiesPaneView_PropertiesPaneUiBinderImpl_GenCss_style-expanded">
                     <div style="position: relative; overflow-x: hidden; overflow-y: hidden; " __gwtcellbasedwidgetimpldispatchingfocus="true" __gwtcellbasedwidgetimpldispatchingblur="true">
                         ....
                     </div>
                 </div>
             </td>
         </tr>
     </tbody>
 </table>
 

The upper div has the right width and height, but somehow the DataGrid div has 1px height and 0px width (at list according to the chrome developer tool)

<div class="GKQJTVMDBNC-com-mycode-management-client-ui-panels-PropertiesPaneView_PropertiesPaneUiBinderImpl_GenCss_style-expanded">
 

Any idea?

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