First off let me start by saying Infragistics did a great job with these controls, I am still new to the Infragistics world but my days are spent less on designing the ui and more on coding now. Any way to the point, I am not sure if the below info is intended functionality or not so I figured I would ask for future reference.
1.) Win Combo.
a. Description: When placed on an Infragistics Tab Control. If you click the dropdown and do not select a row, the code below does not work and the window will not close.
b. CODE: TabControl.PerformAction(Infragistics.Win.UltraWinTabControl.UltraTabControlAction.SelectTabPreviousPage);
c. CODE: TabControl.PerformAction(Infragistics.Win.UltraWinTabControl.UltraTabControlAction.SelectTabNextPage);
d. MY FIX: Change the Limit To List property to false. Validate row data against stored array.
If LimitToList is on, the combo will not permit itself to lose focus. Therefore, you can't change tabs. That's correct behavior.
If the WinCombo has an AllowNull property, you might be able to set that to true and that should allow the control to accept null as well as anything on the list.
Otherwise, you will need to validate the list yourself or maybe add a null item to the list.