I've been using the following code to issue clicks programmatically on a Mac

void PostMouseEvent(CGMouseButton button, CGEventType type, const CGPoint point) 
{
    CGEventRef theEvent = CGEventCreateMouseEvent(NULL, type, point, button);
    CGEventSetType(theEvent, type);
    CGEventPost(kCGHIDEventTap, theEvent);
    CFRelease(theEvent);
}

void Click(const CGPoint point) 
{
    PostMouseEvent(kCGMouseButtonLeft, kCGEventMouseMoved, point);
    NSLog(@"Click!");
    PostMouseEvent(kCGMouseButtonLeft, kCGEventLeftMouseDown, point);
    PostMouseEvent(kCGMouseButtonLeft, kCGEventLeftMouseUp, point);
}

Now, I'm trying to click down to be able to drag objects, like a scroll bar or an application's window. I'm using the following:

PostMouseEvent(kCGMouseButtonLeft, kCGEventMouseMoved, point);
NSLog(@"Click Down!");
PostMouseEvent(kCGMouseButtonLeft, kCGEventLeftMouseDown, point);

When i ran the code above something interesting will happen, when the left mouse down is issue nothing seem to happen, I move my mouse and the window doesn't move, however when I added a mouse up event then the window jumped to the location where I supposedly dragged it. this is sort of OK, however, how do I can make the mouse click down and drag an object?

Note: I do have a whole method to see when the mouse stopped moving so I can click up.

please post code. Thanks