- the "Equal to (at least one)" operator is displayed in the same listbox as "Equal to" and "Contains" ;
- this filter item can have multiple input value field ;
- one input value field has to be filled (required) like on the other filter items ;
- when extended_search is `title: ( "One" OR "Two" )`, behavior changed :

    ________before________  ______________now______________

         Filter Editor               Filter Editor
    [ At least one (OR) v]  [ All criterions (AND)______ v]
    [-][ Title_________ v]  [-][ Title__________________ v]
       [ Equal to______ v]     [ Equal to (at least one) v]
       [ One___________ x]     [ One____________________ x]
    [-][ Title_________ v]     [ Two____________________ x]
       [ Equal to______ v]     [ _______________________  ]
       [ Two___________ x]  [+]
    [+]

         Search bar                  Search bar
    [One][Two][ _______  ]  [One][Two][ ________________  ]