Expose .move_to_top for Window

[darthdeus]

Is your feature request related to a problem? Please describe.
I'm drawing multiple windows which expand their contents on hover (screenshot). The problem is in setting which window is rendered on top.

I tried changing the order in which window.show(...) is called but it seems as long as they have the same IDs their z-order remains the same.

I also tried using ui.with_layer_id but this doesn't work for the windows themselves, as in

Window::new(...).show(|ui| {
  ui.with_layer_id(...);
})

What I noticed happens is clicking on a window puts it in front of all other windows. I tried using ui.request_focus() but this also doesn't work.

The only solution I found digging into egui's source code is

let window = Window::new(...);

ctx.memory().areas.move_to_top(window.area.layer());

window.show(ctx, |ui| { ... });

but the problem is memory().areas and window.area are both private fields. I did this by just making them public with a crate override, but there probably is a reason for them being not directly accessible.

Describe the solution you'd like
Expose an API for Window that enables moving it to the front like areas.move_to_top() does.

Describe alternatives you've considered
I've considered simulating a click on the window, but couldn't find an easy way of doing this. It seems .move_to_top() is only called based on interaction events, but since in my case the UI actually responds to a click I would need to do something more complicated.

In my case clicking removes the item & window, so the only way to move it to the front is click & hold, move the mouse away, and release, which moves the window to the front without triggering click.

[PPakalns]

I had the same problem.

Answer provided in discussion worked for me.
#3493