ASP.NET Splitter - Collapse/Expand fixed panel

Click on the arrow of the splitter separator.
The left panel of the splitter will collapse.
Click again to expand the left panel back.
The splitter panels are fixed when trying to rezise.

The feature also works in horizontal splitter.

Example code

    <obspl:Splitter CollapsePanel="left" IsResizable="false" id="spl1" runat="server" StyleFolder="styles/default">
                ... Left Panel content here ...

spl1.CollapsePanel = VerticalCollapsePanelType.left
spl1.IsResizable = false

spl1.CollapsePanel = VerticalCollapsePanelType.right;
spl1.IsResizable = false;