I’d like to signal a strange behaviour of the latest version of the ModalPopupExtender control that I’ve just noticed. Let’s suppose we have this scenario: two ModalPopupExtender with different TargetControlID but same PopupControlID and DropShadow=”true”. Well, with the latest version of the control, when you click on one of the two controls TargetControlID, the client-side framework throws the following exception:
“Sys.InvalidOperationException: Two components with the same id ’<PopupControlID>$DropShadowBehaviour’ can’t be added to the application”
As you can notice immediately, it seems a problem concerning the DropShadow property of the ModalPopuExtender. In fact, if you set it to “false”, magically everything works fine. I’m very disappointed about this seeming bug because in the previous version of AjaxControlToolkit this control worked regularly in this simple scenario.