[Missing Category] Multi-Window Application support

[KilianHanich]

Multi-Window application are applications which have use multiple windows for very different purposes. These are for example scientific applications, GIMP in multi-window mode and some IDEs. SO all in all huge scientific applications.

While XWayland does support this, Wayland itself does not, meaning that these applications can't be ported.

There are a lot of tries to solve this, but there is always a LOT of bikeshedding involved:

• https://gitlab.freedesktop.org/wayland/wayland-protocols/-/merge_requests/249
• https://gitlab.freedesktop.org/wayland/wayland-protocols/-/merge_requests/264
• https://gitlab.freedesktop.org/wayland/wayland-protocols/-/merge_requests/247

These types of applications are normally assign each window different icons for easier clarification to the user. But the tries to solve that, involves even more bikeshedding:

• https://gitlab.freedesktop.org/wayland/wayland-protocols/-/issues/52
• https://gitlab.freedesktop.org/wayland/wayland-protocols/-/merge_requests/269