But for the most used desktop environment have no support ?? I think this is not acceptable. All major distros offer KDE as a desktop environment. Some - like OpenSuse - also as a standard.
Ultimately it's up to the JRiver devs to decide what distro/desktop environment to officially support on GNU/Linux, which is currently only Debian Wheezy for 32-bit and Debian Jessie for 64-bit (and I guess by extension GNOME as it's the default DE for Debian since Jessie). All other distros; Ubuntu, Linux Mint, Arch Linux, Fedora, OpenSUSE, Slackware, etc. are unofficially supported (and I suppose by extension all other DEs besides GNOME), usually only supported by the community itself (e.g. tutorials by myself and others) and not by the JRiver devs.
Thoughts Bob? Jim? Hendrik?
Personally, I've only tried out KDE a couple times a few years ago, however I've heard good things about KDE Plasma but yet to give it a try. I only use Unity and GNOME in my desktop Ubuntu/Arch Linux installs and Unity, GNOME and Cinnamon in all my virtual machines. I'm not sure about this issue though. Perhaps it's an X/Compiz bug or a graphics driver bug or even a skin bug in MC? Not sure.