Mouse click detecting bug in PopupMenu

[pflugshaupt]

I also see issues with the recent changes:

Regression in parented PopupMenu mouse behaviour in JUCE 8.0.4

Since updating from 8.0.3 to 8.0.4 juce::PopupMenu is broken in some cases when using a menu inside a parent component using withParentComponent(). I like to make juce::Buttons that trigger menus on mouseDown (using setTriggeredOnMouseDown() and allow the user to make a selection with one gesture on the next mouseUp. The users clicks the button, drags to the item to select and releases. This worked fine up to JUCE 8.0.3. It still works fine if the PopupMenu uses an independent window, but is n…