[Pharo-dev] Suspending a Process

I want to create a process doing some work and call #changed on a Morph. I want to start/suspend/resume or stop this process. But sometimes, suspending the process locks the UI-Process, and I don't know why. Did I miss something or do I have to care when to call suspend? Wrapping the "morph changed" call in UIManager default defer:[ morph changed]. Does not change anything. Here is an example to reproduce it. Create the process, call resume, call supsend. It works, most of the time, but sometimes, calling suspend locks the ui. p:=[[true] whileTrue:[ Transcript crShow: (DateAndTime now asString). 30 milliSeconds asDelay wait]] newProcess. p resume. p suspend. regards Nicolai