[Crysstalis]

Not all features of Windows 11 can be bolted on to legacy Win32 APIs. Some features can but others cannot. GTK is not different in this regard. Some features have stayed the same but others have changed and require porting.

If the suggestion is that GTK should somehow get the same budget that Microsoft has to put towards backwards compatibility, you know very well this is not possible. It would probably not even be wanted, GTK is a lot less popular than Windows.

[badsectoracula]

Win32 programs from 2000 work on the latest Win32 and get new functionality that is exposed through the APIs they used at the time, where that applies.

Gtk programs from 2000 do not work on the latest Gtk, regardless of if the functionality they used from the APIs they relied on would be found in the latest Gtk. Instead they have to be "ported" to the new Gtk, assuming the source code is available, the developers are available and someone is willing to waste effort and time to do the porting.

[Crysstalis]

This is a nonsensical comparison though. New versions of GTK are actually new APIs. So what you are saying is more like "WPF programs do not work if you delete WPF and try to compile it against only the Win32 API" which is also correct. GTK1 programs will continue to work on GTK1, it has not changed.