On 1/20/2012 1:57 PM, Peter Litwinowicz wrote: Won't launching a separate app (and waiting on it) cause similar dead-locks? I ask because I'm having similar looking dead-locks when attempting to set parameter values after returning from my app. Paul M., I actually see two different hanging bugs: 1) calling an alert dialog box in –parameterChanged causes FCP to hang and 2) if I take out my alert call I also see FCP hang when trying to change a param value in –parameterChanged (of course, this is the whole point of using –parameterChanged, right?) So perhaps you are seeing the second bug, while I'm seeing both? If you take out setting the params, does FCP still hang? _______________________________________________ Do not post admin requests to the list. They will be ignored. Pro-apps-dev mailing list (Pro-apps-dev@lists.apple.com) Help/Unsubscribe/Update your Subscription: https://lists.apple.com/mailman/options/pro-apps-dev/site_archiver%40lists.a... This email sent to site_archiver@lists.apple.com Yeah, I think so. It seems any parameters I twiddle (inside parameterChanged) BEFORE blocking are properly registered. If I block for awhile and try to change any when I come back, it usually hangs. I have been able to twiddle parameters (without blocking) in parameterChanged successfully, with the most recent version of FCPX. Unfortunately, without custom UI support, I can't implement my fancy UI any other way than launching an external app. So FCPX is still somewhat of a no-go for us right now.