The WebSplitter™ control sizes all panes by pixels. If you specify a percentage amount for a pane, WebSplitter converts the percentage to pixels at run time and exposes that number to you. If you specify percentage values at design time, and the end user resizes a pane, WebSplitter will recalculate the percentage width based on the known width of the browser window and the surrounding panels. WebSplitter will expose the updated percentage value to you