Dialogs on JDesktop get invisible when moving them!

My frame uses a JDesktopPane and JInternalFrames. When I open a dialog through JOptionPane.showMessageDialog or open JFileChooser, those dialogs appear correctly on my desktop but when I move them with the mouse, they get invisible! As those dialogs are modal, the application seems to be frozen as the mouse clicks don't have an effect. I can press ESC to silently close the dialog and then the app continues working. (Enabling LIVE_DRAG_MODE didn't help)

Is this a known problem with dialogs on JDesktopPane?

[525 byte] By [MartinHilperta] at [2007-11-26 13:49:23]