Thanks a lot ! Using OpenerElementID with the NavigateURL set to Response.ApplyAppPathModifier(page) worked great here.
I just have one more challenge that remains. My UserControl contains a Panel, that I want to Ajaxify when the RadWindow closes (as the OnClientClose method of the RadWindow makes an Ajax call handled by the AjaxManager).
So, In the Page_Load method of the UserControl, I add the Panel in the AjaxSettings of the AjaxManager.
protected void Page_Load(object sender, EventArgs e)
RadAjaxManager manager = RadAjaxManager.GetCurrent(Page);
manager.AjaxRequest += new RadAjaxControl.AjaxRequestDelegate(manager_AjaxRequest);
UploadWindow.NavigateUrl = Response.ApplyAppPathModifier("/Pages/UploadFile.aspx?Action=Add");
//If the Parent control is already an Ajaxified Panel then there is no need to Ajaxify the FileLinksPanel
if (!(this.Parent is Panel))
It works fine for the first instance of the control, but the subsequent instances do not have the Panel Ajaxified. How do I solve this ?