After the latest upgrade to Mythbuntu 12.04 we found the previous keyboard shortcut to open the main menu was no longer working. Our solution was to remove the shortcut for CTRL-ESC from
/etc/xdg/xfce4/xfconf/xfce-perchannel-xml/xfce4-keyboard-shortcuts.xml
/etc/xdg/xdg-mythbuntu/xfce4/xfconf/xfce-perchannel-xml/xfce4-keyboard-shortcuts.xml
We then adjusted
~/.config/xfce4/xfconf/xfce-perchannel-xml/xfce4-keyboard-shortcuts.xml
to include the line
<property name=”<Primary>Escape” type=”string” value=”xfce4-popup-applicationsmenu”></property>
in the <property name=”custom” type=”empty”> section.
This can be confirmed in the keyboard section of xfce4-settings-manager. xfce4-settings-manager is not to be run remotely. If you run it with “sudo” you will adjust the wrong settings file.