[QNX]How to get screen resolution?


We have almost ported our game to Blackberry playbook. The game is adopted for various screen resolution, but i cant find how to get actual resolution for this part of code
CC_BREAK_IF(! pMainWnd || !pMainWnd->Create(640, 1092)); //playbook

I’ve only found
screen_window_t screen_window = 0; int size[2] = {0,0}; screen_get_window_property_iv(screen_window, SCREEN_PROPERTY_SIZE, size); CCLog("Screen size is %d %d", size[0], size[1]);

but i dont know where to get screen_window variable.
Any suggestions?