I am using Linux Mint 14 XFCE. I am trying to remove the default XFCE window manager shortcuts for workspace switching (Ctrl-F1, Ctrl-F2, etc.), as described in this question.
The answers there don't have any effect for me. If I go into Settings->Window Manger->Keyboard, nothing I do has any effect. If I click on a setting and hit "Clear", the setting stays there unchanged. If I double-click on a setting and choose a new shortcut key, the original settings stays there unchanged. If I go into Settings Editor (as described in the other answer to that question) and attempt to reset the settings there, nothing has any effect still.
What is going on? How can I get XFCE to let me change the keyboard shortcut settings?