Hi,
I've been testing a UI in C# using API without the TestStand (3.5) User Interface Controls, but it seems that user defined messages are delayed/queued somehow. (Here we only have one UI message event handler for all messages).
Using the ApplicationMgr & ExecutionViewMgr's (the ActiveX UI control way) works perfect. In this case we have UIMessage events through ApplicationMgr and user defined ones through ExecutionViewMgr.