Sylpheed under plasma5 has no menu-bar, no way to access settings

Sylpheed 3.5 doesn’t have a menu bar or a way to set one up, hence no way to get to general or account settings. Gimp has a similar problem but in that case right-clicking in the window gives access to a menu structure and in that menu structure is an item to show a menu-bar …checking it however has no effect! Is someone declaring war on the conventional menu bar right below the title bar?

Remove the unity-gtk-module:

sudo zypper remove unity-gtk-module

I caught a similar piece of advice on usenet without zypper so I then deleted it via Yast. It worked, thanks to you also.