function get_form_element(form_name, element_name) {
	var elem = document.forms[form_name];
	if (!elem) return false;

	elem = elem.elements[element_name];
	if (!elem) return false;

	return elem;
}

function change_form_element(form_name, element_name, value) {
	var elem = get_form_element(form_name, element_name);

	if (!elem) return false;

	elem.value = value;

	return true;
}

var form_submit_finished = false;
function form_submit(form_name, double_click_nocheck) {
	if (form_submit_finished) {
		alert('現在、処理中です。');
		return false;
	}

	var form = document.forms[form_name];
	if (!form) return false;

	// ダブルクリックチェックする場合のみ、フラグを立てる。
	if (!double_click_nocheck) form_submit_finished = true;
	form.submit();

	return false;
}

function change_submit_form_element(form_name, element_name, value, double_click_nocheck) {
	if (change_form_element(form_name, element_name, value)) {
		return form_submit(form_name, double_click_nocheck);
	} else {
		return false
	}
}

function change_action(form_name, url) {
	var form = document.forms[form_name];
	if (!form) return false;

	form.action = url;

	return true;
}

function get_options_selected_value(form_name, element_name) {
	var elem = get_form_element(form_name, element_name);

	if (!elem) return false;

	var sel = elem.selectedIndex;
	var opt = elem.options[sel];

	return opt.value;
}