Event which is fired when a treegrid row(for the most parent layout) is about to be expanded. Return false in order to cancel row expanding. Use args.owner to access the treegrid object. Use args.row to access a row element(for the most parent layout) that should be expanded(jQuery representation). Use args.fixedRow to access a (top most parent)fixed row element that is about to expanded(jQuery representation). If there aren't fixed columns it is undefined. Use args.dataLevel to access the databound level of the topmost treegrid row to be expanded.
Target Platforms: Windows 8.1, Windows 8.1, Windows 8, Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2