Deprecate menu bar with CSD

[RocketMan]

When CSD is enabled, lose the menu bar and migrate its functionailty to the CSD header. This will make the UI consistent with other GNOME 3 applications.

[ashaduri]

Hi,

While I understand the wish to have a consistent desktop, GSmartControl is not a GNOME application.

It also seems that there is no global (or desktop-specific) CSD switch, so the CSD-loving applications are always displayed with (inconsistent) CSD, even in non-CSD desktops like KDE Plasma.

So, patches are welcome as long as they do not break the regular title bar in other desktops, Windows, or macOS. (As an example of bad design, the new versions of gedit look completely out of place in KDE Plasma due to built-in CSD; the old versions were fine).

On a personal note, I quite dislike the current design trends in GNOME, so it is unlikely that I will be implementing this myself.