I'm not sure if it is a OSX specific thing or specific to Ableton Live 8.
The issue I'm seeing is that when I try to close the plugin window the window stay but is just white, except the border that the OS draws.
This happens with my JUCE plugins and with JuceDemoPlugin, Curve2CM (which I think is made with JUCE) but not with my older plugins I have not made with juce and not with a number of other plugins.
It seems from my limited testing setup that JUCE is the common thing. It doesn't seem to matter which JUCE version. A new build made with JUCE4 works the same as older made with JUCE3.
Test setup OSX 10.11.1 and Ableton Live 32bit 8.2.8