when you refer to the other property you can simply use the name, the categories shouldn't matter.  You can even do something like

URL.toString() != "" 

 

site is simply a category in the config.xml file 

ok but when I can create multiple url:s

 and I want to display the url property if the corresponding type property value is set to http

 

perhaps this can not be done? 

 

displying diffrent number of properties depending on a type property is each created category.