Capturing a window in Wayland does not scale properly

[rommeswi]

Steps to reproduce:

• Start Weylus on Wayland (pipewire).
• Have a window open that occupies half the screen.
• Open browser link.
• Share only the window.

Expected result:

• Weylus chooses the canvas size properly so that the incoming video has the canvas size of the window and can occupy the full browser screen.

Actual result:

• Weylus displays a canvas the size of the screen the original window is placed on. The area unoccupied by the window remains black. Since Weylus does not allow to "zoom in" on the browser, only half the screen of the tablet can be used.

[rommeswi]

I noticed that the behavior is in some sense even worse. Specifically, when clicking or touching "outside" the window, it will actually register as a click in that application. This does not seem to be in line with Wayland's idea of only giving access to the specific application. If I share only a window of "Xournal", then Weylus should not be able to click in another window of "System Settings".

This seems to be a (perhaps minor) security issue. If I share a Xournal window with another person, Weylus currently allows the one who has access to execute a script that (given they know the desktop environment's default behavior and placement) quickly accesses the system settings of that desktop environment. From the perspective of the user, it however looks like access is only granted to the Xournal window.