DevTools Window: Fix glitches with window management

[sellmair]

The 'floating' sidecard can have weird behaviours on different window managers.
We shall find a reliable way of rendering it in a wide variety of environments

[Nohus]

If the target plan is to have the tooling be an IntelliJ plugin, with the UI being in the IDE, then I wonder if it's worth investing time in the sidecar window at all. Or are you planning to keep it even then?

[sellmair]

We will keep some visual feedback near the running application to ensure devs are aware of the state of the application at a quick glance

[Nohus]

Maybe a way to avoid all the window management issues would be to have the UI overlaid over the client application window, instead of a separate window coming from CHR. For example the colored status border could be shown around window frame instead of next to it in it's own window.

I'm also thinking of the case of working on fullscreen apps, where the sidecar becomes inaccessible.