Stutter due to locking when creating AudioProcessorEditor

[ed95]

This is the thread that lead to that commit for some context:

Fixed minor race condition and priority inversion

Hello, I think there is a potential race condition in AudioProcessor::createEditorIfNeeded if called from several threads : multiple editors could be created. The fix would be to take the lock earlier in the method. Also, it can be a dedicated CriticalSection imho (or does it absolutely need to be the callback CriticalSection?), so in the fix I proposed hereunder I add a CriticalSection dedicated to the protection of the access to activeEditor member. This will also prevent priority inversion…

It’s hard to see how removing the callback lock from the editor creation/destruction would cause audio dropouts as now there is a separate critical section to lock around access to the active editor which isn’t used around the processBlock calls. Are you perhaps taking the callback lock somewhere in your plug-in via AudioProcessor::getCallbackLock()?

Are you able to put together a simple example which reproduces this? I’ve taken the audio plug-in template and modified it to output a continuous sine wave and I can’t hear any audio dropouts when closing/opening the editor in Live 10.1 (VST3, AU or VST).