var checkflag = "false";

	function selectAll(field){
      var outer_field = document.forms[0].elements[field];
      for (i = 0; i < outer_field.length; i++){
      var field = outer_field[i];
      if (checkflag == "false") {
        for (i = 0; i < field.length; i++) {
        field[i].checked = true;}
        checkflag = "true";
        return " auswahl löschen "; 
      }
      else {
        for (i = 0; i < field.length; i++) {
        field[i].checked = false; }
        checkflag = "false";
        return " alle auswählen "; }
      }
  
  }

function checkAll(obj_set_name,sel_mode)
{
    var checkboxes = document.getElementsByName(obj_set_name);
    var total_boxes = checkboxes.length;
   
    for(i=0; i<total_boxes; i++ )
   {
    current_value = checkboxes[i].checked;
  
   if(current_value != sel_mode)
   {
      checkboxes[i].checked = sel_mode;
    }
  }

}


function checkTrainer(check_sel,check_sel2_name)
{
    var checkboxes = document.getElementsByName(check_sel2_name);
    var total_boxes = checkboxes.length;
    var sel_index = check_sel[check_sel.selectedIndex].value
   
    for(i=0; i<total_boxes; i++ )
   {
   
    	if(checkboxes[i].checked == false && checkboxes[i].value==sel_index) {
				alert("Der Haupttrainer ist nicht gebucht");
				check_sel.selectedIndex  = 0;
			}
  
   	
  }

}