MDI (Multiple document interface)

Description

Can we have multiple document interface support in MAUI?
It may be a outdated pattern for the most part, but it's still very useful for game editors but its also good for small single monitors.

While it may take some work behind the scenes of the maui api.
It's public api is as simple as letting the user assign a window or control to another window's parent.

Public API Changes

var window = new Window();
var subWindow = new Window();
subWindow.Parent = window;
// or
var control = new Control();
var subWindow = new Window();
subWindow.Parent = control;

Intended Use-Case

For me it would be used in gamedev, however I have seen dentist offices use winforms MDI for their apps due to being limited to 1 small screen.

The issue names MAUI's Window and Control types and proposes assigning a subwindow's Parent; no files, tests, or entry points are identified. Start by locating the existing Window and Control APIs and determining how the proposed parent relationship should work across MAUI's supported desktop targets. Done means the described MDI use case and public API are supported.