AutoCompleteExtender highlighted text truncation

Hi,

I have a text box with autocomplete extender attached, showing the results in an associated panel. Here is the relevant code:

<asp:TextBox ID="st" runat="server" Wrap="False"></asp:TextBox><asp:Panel runat="server" ID="stPanel" Wrap="False" ScrollBars="Horizontal" /><asp:AutoCompleteExtender ID="stex" runat="server" DelimiterCharacters="" Enabled="True"
         ServiceMethod="GetAlike" ServicePath="sbox.asmx" ClientIDMode="Static"
         TargetControlID="st" UseContextKey="True" MinimumPrefixLength="2"
         CompletionInterval="300" CompletionSetCount="20" CompletionListElementID="stPanel"></asp:AutoCompleteExtender>

The problem is that when an item from the result list is selected with length bigger than panel’s width, and you scroll horizontally, the item’s text is truncated to the originally displayed portion, i.e. the hidden part is not shown:

I have tried to solve the problem with some CSS to “CompletionListHighlightedItemCssClass” property but without success.

Please, help with an advice or a solution, thanks!