I observed that top item background of UltraWebMenu is not rendering in page where i use WebDialogWindow for example i use predefined theme LucidaDream in which top item background it's rendering normal like lightblue but if page contains a WebDialogWindow that it's rendering with white this think i observed in another case at modified theme with UltraWebListBar that has problem with rendering Item background(not group background) instead of rendering background with color which i setted it's rendering UltraWebListBar background item with white.
I find the problem, how is normal the problem come from css, after i looked with IE Developer Explorer at what css classes use this parts which doesn't rendering corect i observed that this tags has assgined multiple css class like this
<div width="100%" class="ig_LucidDreamItem iglb_LucidDreamItem" align="Center" title="Add Persons" id="uwls_0_Item_0">
every component have a css file with classes defined for each element(iglb_LucidDreamItem) but exist a css shared file which contain global css classes ig_LucidDreamItem, solution was to remove background of ig_LucidDreamItem css class which was white and which cause the problem of rendering, i hope that post to be useful for others which meet this problem