I’ve implemented a fully resizable GUI in my upcoming plugin (thanks for the help on that, Jules!). One thing I have noticed: The resizing of the Audio Unit GUI is very jittery. I have constrained the proportions of my GUI, and there are all sorts of white blocks behind the GUI that momentarily emerge during the resizing process. A similar thing happens with the Juce demo plugin. For some reason, the VST resizing is much smoother - no jitter in Live, while the AU in Live has lots of resizing jitter.
Any explanations on why the resizing is jittery for Audio Units? And is it fixable, or is it one of those AU things that we just have to deal with?