I tried my Logitech Rumble Gamepad with some gba games and recognized that the dpad is not working properly.
When i press up or down and switch to the left or right ones, the input is not accepted. It only works if i release the pressed button and press left or right afterwards.
Vice versa, the switch from left or right to up or down works without problems. Using the Keyboard or a game not designed for game boy advance does not result in that error.
By the way i'm using the Windows-Wx 2.0.0 beta 2 version from sourceforge.