the output of DialogBox is very strange

I just want to show a dialogbox when press a button. the code is very
simple:
final SimpleSearchResultPanel test = new SimpleSearchResultPanel();
btnTest.addClickHandler(new ClickHandler(){

@Override
public void onClick(ClickEvent event) {
// TODO Auto-generated method stub
test.setSize("1000px", "800px");
test.setGlassEnabled(true);
test.center();
test.show();
}

});

and SimpleSearchResultPanel is a DialogBox
import com.google.gwt.dom.client.Style.Unit;
import com.google.gwt.user.client.ui.DialogBox;
public class SimpleSearchResultPanel extends DialogBox {

SimpleSearchResultPanel(){
super();
this.setGlassEnabled(true);
}
}

but when the dialog box is shown, it is very strange, it has many
line, strange image that do not know where is come from!!
the application is run in IE8.
anyone know what happens?

--
You received this message because you are subscribed to the Google Groups "Google Web Toolkit" group.
To post to this group, send email to google-web-toolkit@googlegroups.com.
To unsubscribe from this group, send email to google-web-toolkit+unsubscribe@googlegroups.com.
For more options, visit this group at http://groups.google.com/group/google-web-toolkit?hl=en.