I updated from 8.0.3 to 8.0.4. Now, in my popup menus with CustomComponents, I can no longer select an item with the mouse. Clicking on the item does nothing.
It seems perhaps the same issue as this:
If I implement the same fix he suggests, then they work again.
Alternately, all of my popup menus have the MainComponent set as the ParentComponent, by overriding LookAndFeel::getParentComponentForMenuOptions().
If I remove that so they are free-floating, then the mouse works to select items once again.