rem: WMPoint wGetPointToCenterRectInHead(WScreen *scr, int head, int width, int height)
add: wGetPointToCenterRectInHead(WScreen *scr, int head, int width, int height)
context: WMPoint wGetPointToCenterRectInHead(WScreen *scr, int head, int width, int height){    WMPoint p;    WMRect rect = wGetRectForHead(scr, head);    p.x = rect.pos.x + (rect.size.width - width)/2;    p.y = rect.pos.y + (rect.size.height - height)/2;    return p;}