Java HotSpot Virtual Machine

I am writing a C++ plugin for a GUI Windows app. When triggered, my plugin needs to make a JNI call to present a modal Swing dialog, block until the user makes a selection, and then return control to the native application.

I've gotten the Java dialog to work OK by running a Windows message pump on the main thread (I really don't know Windows well enough to know what I'm doing here) and starting a separate thread in Java, which posts the Java GUI action onto the EventQueue. I'm also creating a WEmbeddedFrame with the HWND of the main native window and passing that in as the owner for the JDialog.

The main problem that I'm having is that while my C++ plugin is blocked waiting for user input, the native GUI app in the background usually does not redraw - if the user drags the Java modal dialog around, it leaves a white trail on the window contents behind it. I say 'usually' because sometimes it blanks out the native background window completely when the Swing dialog is displayed.

Any suggestions? I am happy to hire somebody to help with this, if you know how to make this work.