As explained in MSDN http://msdn2.microsoft.com/en-us/library/ms644959(VS.85).aspx "A global hook monitors messages for all threads in the same desktop as the calling thread. ... A global hook procedure can be called in the context of any application in the same desktop as the calling thread, so the procedure must be in a separate DLL module... "

In this case you are trying to install a global hook so it must be in a dll so it can be injected into other processed. The problem with implementing this in java and jna is that no JVM might exist in the process so you might need to start one, which will probably be slow and quite a lot of resources and I think it will need native code to make this work, not just JNA. http://msdn2.microsoft.com/en-us/library/ms644959(VS.85).aspx

An easier approach is to use global hotkeys. Your window will get a message when you press certain key (might be with modifiers like Ctrl,Alt, etc. but I think it works fine even without modifiers) , and you can just ignore it. Use RegisterHotKey function for registering the hotkeys: http://msdn2.microsoft.com/en-us/library/ms646309.aspx Thanks, Daniel