On Windows 98 I'm continually getting a ghost window in the task bar after exiting a fullscreen app. I know elias fixed the same problem for windowed mode (which works fine), and I don't recall seeing it with fullscreen in the past. Anyway, I can't figure out what's causing it. The only workaround I've been able to figure out for now is:
in win32/org_lwjgl_opengl_Window.cpp - closeWindow()
add: ShowWindow(hwnd, SW_HIDE)
right before the call to DestroyWindow()