Hi James,
UserControl_OnLoad is not the correct place to do customization of DockingManager. Please refer to the below KB and let me know if it helps.
Is the Form.Load event handler a good place to perform custom initialization of the docking layout?
Code snippet:
private void dockingManager1_NewDockStateEndLoad(object sender, EventArgs e)
{
if (this.flag)
{
this.flag = false;
Icon iIcon = new Icon("App.ico");
this.dockingManager1.SetDockIcon(this.treeView1, iIcon);
}
}
Thank you for using Syncfusion products.
Regards,
Murugan P.S