Spark skinning - combobox transparent background issue

Question

Hi,
I have a custom combobox component whose background is transparent when it is in a titlewindow , but looks opaque in a cell of a datagrid. The code for background for combobox is
<!--- Defines the appearance of drop-down list's background fill. -->
<s:Rect id="background" left="1" right="1" top="1" bottom="1" >
<s:fill>
<!---@private
The color of the drop down's background fill.
The default color is 0xFFFFFF.
-->
<s:SolidColor id="bgFill" color="0xFFFFFF"/>
</s:fill>
</s:Rect>
The code for background fill of titlewindow is
<!-- layer 2: background fill -->
<!--- Defines the appearance of the TitleWindowSkin class's background. -->
<s:Rect id="background" left="1" top="1" right="1" bottom="1">
<s:fill>
<!--- Defines the TitleWindowSkin class's background fill. The default color is 0xFFFFFF. -->
<s:SolidColor id="backgroundFill" color="#FFFFFF"/>
</s:fill>
 </s:Rect>
Though setting the alpha to 1 in either code did not work. Please help.

Answer 1

Setting of contentBackgroundAlpha for the combobox worked.