Следующие должны сделать -
CGRect rect;
uint32_t windowid[1] = {windowID};
CFArrayRef windowArray = CFArrayCreate ( NULL, (const void **)windowid, 1 ,NULL);
CFArrayRef windowsdescription = CGWindowListCreateDescriptionFromArray(windowArray);
CFDictionaryRef windowdescription = (CFDictionaryRef)CFArrayGetValueAtIndex ((CFArrayRef)windowsdescription, 0);
if(CFDictionaryContainsKey(windowdescription, kCGWindowBounds))
{
CFDictionaryRef bounds = (CFDictionaryRef)CFDictionaryGetValue (windowdescription, kCGWindowBounds);
if(bounds)
{
CGRectMakeWithDictionaryRepresentation(bounds, &rect);
}
}
CFRelease(windowArray);