There is a problem with simple custom tags. I have a GroupingTag which encapsulates a simple fieldset tag from
html. Its derived from AbstractClosingUITag.

Here is the code:
=================
package com.foo.package;

import com.opensymphony.webwork.views.jsp.ui.AbstractClosingUITag;
import com.opensymphony.xwork.util.OgnlValueStack;

public class GroupingTag extends AbstractClosingUITag {

public final static String OPEN_TEMPLATE = "s1_grouping.vm";
  public final static String TEMPLATE = "s1_grouping_end.vm";

private String legend;

public String getDefaultOpenTemplate() {
     return OPEN_TEMPLATE;
  }

protected String getDefaultTemplate() {
     return TEMPLATE;
  }

public void setLegend(String legend) {
     this.legend = legend;
  }

protected void evaluateParams(OgnlValueStack stack) {
     super.evaluateParams(stack);
     if (legend != null) {
        addParameter("legend", findValue(legend, String.class));
     }
  }
}

This tag works fine for ordering and logical grouping of different
parts on my pages. I use them in this way:

#bodytag (Grouping "id=msGrp" "legend='The legend of the tag'" )
some stuff to be grouped togehter ;-)
#end

but when i try to use it the groupings in a NESTED way, the nested one
is at the beginning of the outer grouping not where it should
be..........in other words, the output is flattened not nested.