Expose more window API - Githubissues

The slint::Window struct has a fairly limited API so far compared to what winit and other framework offer. We should either duplicate most of their capabilities so it can be used from Rust/CPP/JavaScript/Python/...

Some features of the window that relates to the UI itself can be done on the .60 Window element in a declarative way:

[x] Window title (already done with title property)
[x] Window icon (#339)
[ ] Scale factor (read only?)
[x] cursor (not a window property, more like an element property)

The more imperative UI can be done via API: One would need to expose what is currently the ComponentWindow into a public sixtyfps::Window which has function to do a bunch of things.

This include:

[x] Setting the window state: maximized, minimized, fullscreen, normal (#325)
[x] Setting some windows flag (e.g stay_always_on_top (#324), or request_attention, or border_less)
[x] Setting the geometry (#323)
[x] Show/hide which are currently on the component, but also allow setting a callback when the window is requesting to be closed in order to show another dialog and cancel and a getter to know if it is currently shown or hidden.

The items::Window need to be renamed WindowItem to avoid duplicated name (just like ImageItem)

slint-ui / slint

Expose more window API #333