QWindowsContext::findPlatformWindowAt stuck in infinite loop

\qtbase\src\plugins\platforms\windows\qwindowscontext.cpp

There is this line of code that causes an infinite loop if "parent"is not updated.

while (findPlatformWindowHelper(screenPoint, cwex_flags, this, &parent, &result)) {}

This is what happens if the line:

const HWND nonTransparentChild = ChildWindowFromPointEx(*hwnd, point, cwexFlags | CWP_SKIPTRANSPARENT);

returns 'nonTransparentChild' == *hwnd
(that is, the function returns the parent, and not null, and not a child. This is legal, according to the Microsoft ChildWindowFromPointEx description).

I have a case where this happens: the top-level window is a transparent window.

Possible solution that works for me: changing:

*result = nonTransparentWindow;
*hwnd = nonTransparentChild;

To

*result = nonTransparentWindow;
if (*hwnd == nonTransparentChild)
	return false;
*hwnd = nonTransparentChild;