function insertTag(t_open, t_close){
	var t_area = document.getElementById('edit_field');
	
	if (t_area.setSelectionRange > '') {
		var p0 = t_area.selectionStart;
		var p1 = t_area.selectionEnd;
		var top = t_area.scrollTop;
		var str = '';
		var cur0 = p0 + t_open.length;
		var cur1 = p0 + t_open.length + str.length;

		while (p1 > p0 && t_area.value.substring(p1-1, p1) == ' ') p1--; 

		if (p1 > p0) {
			str = t_area.value.substring(p0, p1);
			cur0 = p0 + t_open.length + str.length + t_close.length;
			cur1 = cur0;
		}
		
		t_area.value = t_area.value.substring(0,p0)
		+ t_open + str + t_close
		+ t_area.value.substring(p1);
		t_area.focus();
		t_area.selectionStart = cur0;
		t_area.selectionEnd = cur1;
		t_area.scrollTop = top;

	}
}