$ unset GNOME_DESKTOP_SESSION_ID
$ monodevelop

su
cd /opt/monodevelop && nano monodevelop.sh

#!/bin/bash
unset -v GNOME_DESKTOP_SESSION_ID
cd /usr/bin && ./monodevelop-opt #or monodevelop if exist

chmod +x monodevelop.sh
ln -s /opt/monodevelop/monodevelop.sh /usr/local/bin/monodevelop
cd /usr/share/applications/ && nano monodevelop-opt.desktop #or monodevelop.desktop if exist

Exec=monodevelop %F
TryExec=monodevelop