[Project_owners] about creating sidebar tour

[Jesper Staun Hansen]

Hello all.

I am following 
http://developer.mozilla.org/en/docs/Creating_a_Firefox_sidebar
And tried out the 
http://developer.mozilla.org/samples/extension-samples/emptysidebar.zip 
file and installed it.
But I am having some trouble with this:
<!ENTITY emptysidebar.title "EmptySidebar">
<!ENTITY openEmptySidebar.commandkey "E">
<!ENTITY openEmptySidebar.modifierskey "shift accel">
 From file: locale/en-US/emptysidebar.dtd
At that state, then pressing E and combining shift+E doesn't work.
But if I change "shift accel" to "", then it works when I just press E.

What is the medifierskey for?