server-side decorations: double click to maximize window

[ryanabx]

Here's the related client-side issue on libcosmic: https://github.com/pop-os/libcosmic/issues/323

It'd be nice to be able to double click the title bar in server side decorations to maximize the window.

[Drakulix]

cosmic-comp is using libcosmic and the headerbar widget to realize the server-side decorations. So once the libcosmic issue is solved (and the dependency updated in cosmic-comp) this should just work.

[ryanabx]

What's weird is that libcosmic does have code that talks about double clicking to maximize:

src/widget/header_bar.rs at line 340:

// Assigns a message to emit when the headerbar is double-clicked.
    if let Some(message) = self.on_maximize.clone() {
        widget = widget.on_release(message);
    }

It doesn't seem to be working ootb though with server side decorations. Nor with libcosmic apps

[ryanabx]

I've been told on the mattermost that this is an iced issue upstream. Previously double clicking worked due to a bug, but now iced will need to actually implement double click support on the mousearea widget.