[macOS] Drag and Drop not working : cannot grab icos in Draggable Icons example

Draggable Icons example app does not work with Qt 6.9.0 beta1 on macOS while it works Qt 6.8.1.

How to reproduce the issue : 

1. Run Draggable Icons example application with Qt 6.9.0 beta1 on macOS.
2. Try to drag any icons on the window. You will not be able to drag any of them.

This issue is reproduced with Qt 6.9.0 beta 1 built from source as well, and if you apply the workaround below, the issue will be solved somehow.

<qtbase/src/corelib/kernel/qcore_mac_p.h>

void trackObjectLifetime()
{
 	if (!m_object)
		return;

	auto *lifetimeTracker = [WeakPointerLifetimeTracker new];

	lifetimeTracker.pointer = reinterpret_cast<QObjCWeakPointer<NSObject>*>(this);

	NSObject * wtf = m_object; // <— added by jaf

objc_setAssociatedObject(m_object, this, lifetimeTracker, OBJC_ASSOCIATION_RETAIN); // <—— somehow this sets m_object to NULL!!! --jaf

	m_object = wtf; // <— added by jaf

	[lifetimeTracker release];
}