http://bugs.winehq.org/show_bug.cgi?id=36915
--- Comment #2 from Bruno Jesus 00cpxxx@gmail.com --- Change the line from file dlls/winex11.drv/mouse.c: 466 else if (hwnd == data->clip_hwnd)
To: 466 else if (data && hwnd == data->clip_hwnd)
It may help you move forward (or crash a little bit later), but it's very weird that x11drv_init_thread_data was not called previously to fill the "data" variable.