I have this code and it works.
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>Ejemplo</title>
<script type="text/javascript" src="jquery.js"></script>
<script type="text/javascript" src="jquery-ui.js"></script>
<script type="text/javascript" src="tinymce/jquery.tinymce.min.js"></script>
<script type="text/javascript" src="tinymce/tinymce.min.js"></script>
<link href="jquery-ui.css" rel="stylesheet" type="text/css" />
<script type="text/javascript">
$(document).ready(function() {
$('#txapublicacion').tinymce({
plugins : 'link'
});
//--------------------------------------
$("#lnk_mostrar_form").click(function() {
$("#dv_formulario").dialog("open");
return false;
});
//--------------------------------------
$("#dv_formulario").dialog({
autoOpen : false,
modal : true,
buttons : {
Buscar : function() {
$(this).dialog("close");
},
Cancelar : function() {
$(this).dialog("close");
}
},
close : function() {}
});
//-------------------------------------
});
</script>
</head>
<body>
<a id="lnk_mostrar_form" href="">Formulario</a>
<div id="dv_formulario" title="Ejemplo">
<form id="frm_buscar">
<textarea id="txapublicacion"></textarea>
</form>
</div>
</body>
</html>