when reading e.getNumberOfClicks() in AudioProcessorEditor::mouseDown() I read 4 for a doubleclick instead of 2. Single-Clicks still produce a 1.
I just added a mouseDown to the Demo-Plugins Editor with the same result. Juce is the tip (1.52.87).
I just tested on Win7 with VSTPluginanalyser. I found this problem because a e.getNumberOfClicks()==2 didn’t work and this occured also under Cubase and Reaper on Windows. I haven’t checked on Mac.
I’m quite sure it worked once, so maybe this has something to do with your recent fix to not accept left-right clicks as double-clicks.