Well, there still doesn't seem to be much information out there on how to work around this problem and running an application via remote X11/xinerama makes it practically unusable. In particular, menu navigation takes an eternity. The work-around that we employed has 2 parts to it.
At the startup of your application call:
JPopupMenu.setDefaultLightWeightPopuEnable(false);
This will force the popups to use heavy weight popups. Lightweight popups make multiple calls to the X windows across the network to determine what is visible, obscurred, etc. When operating over remote X11 this becomes a very expensive call. Lightweight popups make these calls everytime the popup becomes visible. Heavyweight popups make this call when they are 1st invoked, but every successive popup action reuses the heavyweight component that I'm guessing is managed by the window manager so the menus thereafter are very responsive.
Create a new XineramaJMenu class that extends JMenu. This class must override the method:
protected Point getPopupMenuOrigin()
{...}
copy the code for this method from JMenu, but replace the line:
Insets screenInsets = toolkit.getScreenInsets(gc);
with
Insets screenInsets = new Insets(0,0,0,0);
This eliminates the getScreenInsets(...) call, which makes multiple calls to the remote X server to determine the max inset values of the child windows. We eliminate this expensive call across the network and accept a default 0 inset.
Unfortunately, this will require you to replace all instances of JMenu with XineramaJMenu, but it at least results in usable menus when running your application over remote X11.
