In Reaper, it is possible to load plug-ins in a separate processes, so not to harm the “main” one with the host, in case one of them crashes (or whatever reason, anyway).
When a JUCE plug-in is opened this way, the window for the editor gets correctly created, but nothing is painted in there, so the content of the window is completely white.
The behaviour is reproducible with the Juce Demo Plug-in from the latest git commit of JUCE.
I am working on MacOS X 10.6, using the 32 bit version of the latest Reaper.
The “load in a different process” option can be found in Reaper’s preferences: Choose the “Plug-ins” entry and select “In separate plug-in process” from the combo labeled “VST/AU bridging/firewalling”
Since the plug-in gets its process when loaded, to attempt a debug I had to start Reaper, load the plug-in and only at that point Attach the XCode debugger to the bridging process. I haven’t been able to do much from there though, because the paint () method seems to be called, but after a few iterations into that the bridging process exited (???)