Datagrid = {

  fixSearchInput: function(){
    a = $$('.dataGridSearchInput');
    for(i=0;i<a.length;i++){
      n = a[i].name;
      n = n.substr(7);
      n = n.substr(0, n.length-1);

      w = $('datagrid_th_'+n).getWidth();
      w-=30;
      a[i].setStyle({
        'width': w+'px'
      });

    }
  }

}

Event.observe(window, 'load', function(){
  Datagrid.fixSearchInput();
});