Display check boxes from select request : Create Region with PL/SQL Type and with following source

declare 

    cursor chk_cur is SELECT 
        id, label
    FROM t_witr
    ORDER BY label;

    ind integer := 1;
    l_chk_selected_ids varchar2(3000) := null;
    l_check_state varchar2(30) := 'CHECKED';

begin

    l_chk_selected_ids := :P1_CHK_SELECTED_IDS;

    htp.prn('<h2>Items selection</h2>');
    htp.prn('<table style="width:100%">');
    for col in chk_cur loop
        if ind mod 2 > 0 then 
            htp.prn('<tr><td>');
        else
            htp.prn('<td>');
        end if;
        if l_chk_selected_ids is not null and length(trim(l_chk_selected_ids)) > 0 and instr(l_chk_selected_ids,'#!' || col.id || '#!') <= 0 then
          l_check_state := 'UNCHECKED';
        else
          l_check_state := 'CHECKED';
        end if;
        htp.prn(apex_item.checkbox(1,col.id,l_check_state));
        htp.prn('<label class="chkLabel">'||col.label||'</label>');
        if ind mod 2 > 0 then 
            htp.prn('</td>');
        else
            htp.prn('</td></tr>');
        end if;

        ind := ind +1;
    end loop;
    htp.prn('</table>');

end;

Create button submit, and then create process executed after submit to save items selection state like following

declare
  l_chk_selected_ids varchar2(3000);

begin
  FOR i in 1..APEX_APPLICATION.G_F01.count
  LOOP
    l_chk_selected_ids := l_chk_selected_ids || '#!' || APEX_APPLICATION.G_F01(i) || '#!';
  END LOOP;
 :P1_CHK_SELECTED_IDS := l_chk_selected_ids;
end;