When setting a WebSplitter's AutoPostBackFlags-SplitterBarPositionChanged=Async (or any other ones) the postback does indeed occur in AJAX (partial postback) but the method that actually manages the response - IG.WebSplitter.prototype._responseComplete() - is using a DOM method which is only supported in IE browsers - line#74 this._element_.swapNode(node) - which throws errors in ALL other browsers (GoogleChrome, Safari, FireFox, etc...) - easy to see in the FireBug debug console.

In fact, the WebSplitter works just fine in all other browsers (even with this error) except for IE - since IE supports this it will replace the currently loaded Panes again reloading any contents (like iframes, ContentUrl, etc...) which is NOT the expected functionality of an Async postback!

The reason for settings this AutoPostBackFlag in the first place was for your own PersistenceFramework to save the WebSplitter layout (panes sizes), but because of this "feature" I can't use either one of them and am forced to manually persist/load (after disabling all AutoPostBackFlags). Not really what you would call "Controls working in harmony" :(

This is all in Visual Studio 2010, .NET 3.5, Infragistics35.Web.v11.2 File version 11.2.20112.2025 under IE 9.0.8112.16421 and GoogleChrome 21.0.1180.79