In my project, i can get the window which mouse is on, and i can use AXUIElementSetAttributeValue(element, kAXFrontmostAttribute, kCFBooleanTrue);
 to make the window to top level temporarily. So i want to convert the element to Cocoa NSWindow and then use makeKeyAndOrderFront to make it always in front. Anyone know how to implement this.
+ (NSArray *)attributeNamesOfUIElement:(AXUIElementRef)element {
    NSArray *attrNames = nil;
    AXUIElementCopyAttributeNames(element, (const void*)&attrNames);
    AXUIElementSetAttributeValue(element, kAXFrontmostAttribute, kCFBooleanTrue);
    // Below lines doesn't work.
    HIObjectRef windowref=AXUIElementGetHIObject(element);
    NSWindow *cocoaWindow = [[NSWindow alloc]initWithWindowRef:windowref];
    return attrNames;
}