Trying to remap Caps Lock in Xubuntu, but Keyboard Layouts Plugin resets everything

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http://askubuntu.com – I am using Keyboard Layouts Plugin to switch between two layouts. I want to remap Caps Lock to underscore "_" First I empty Caps Lock, or otherwise caps lock will do both – toggle caps and produce underscore character and then map caps lock to underscore xmodmap -e "keycode 66 = " xmodmap -e "keycode 66 = underscore" Problem? This resets every time I log out or change something in Keyboard Layouts Plugin preferences. I want this to be permanent. (HowTos)