In my opinion, the task of active window should not flash when it recieves urgency hint. In order to stop it from flashing I have to activate some other window and then switch back to this one. No other task bar that I have used seems to have such a behaviour.
Well, while it is the application task to manage urgency hint and your application seems to fail checking own window state, some window managers ignore it when window has focus, so it should be OK to do the same. I believe your request is completely satisfied in current GIT repository sources. Test it when that is possible for you, please, and tell us if something is still wrong. Thank you very much.