ASP.NET Accordion height messed up when starting in collapsed mode

I have an ASP.NET accordion rendered by this markup (removed some CssClass properties):

<toolkit:Accordion runat="server" AutoSize=开发者_运维问答"Fill" 
    RequireOpenedPane="false" SelectedIndex="0" Height="400">...

This renders OK in terms of height. Now when I change one setting SelectedIndex="-1" to have everything collapsed at load time, the height is messed up when you start opening panes. The visible height remains 400px but the content of the panes is clipped at the bottom even though there is a scrollbar (see screenshot http://awesomescreenshot.com/00e6jj00f). I'm guessing the height of the headers is not subtracted from the pane height in this case. Also when I changed the height property to 300, the same behavior happens with visible height 300. In the css file I only change colors, borders and some padding. No heights or overflow set there.

I tested IE6, IE9 (several modes), Firefox 3, Chrome 8 and Safari 5 (Win).

Does anyone have an idea on how to fix this or what I could be doing wrong?

You can fix this by downloading the source code for the toolkit, fixing the JavaScript in there that calculates the height... recompile amuse the new dll.