Width/Height of screen

[LordVagous]

How do I set the width and height of a window to half the screen?

[Horbin-Magician]

Maybe you need to call the system api to get the screen size or use other crates.

[ogoffart]

You need to use window().set_size with the size which you can compute based on the screen size. To get the screen size, you will need to use another crate.
For example you can get it with private API using the i-slint-backend-winit crate.