expr %a = %4 - %3 + 2
expr %b = %4+1
expr %c = %2+1

menu float0
menuitem "&Open" edit %1
menuitem ""
menuitem "&Change" execute \<ALT_F1>r
menuitem "&Delete" execute "1\<ALT_F2>r
menuitem "&Yank" execute "1\<ALT_F3>r
menuitem "T&oggle case" execute \<ALT_F4>r
menuitem ""
menuitem "&Search" execute \<CTRL_S>%1\n
menuitem "&Fgrep" fgrep "%1"
menuitem "&Tag" tag %1
endmenu

floatmenu 0 %a %b %c