GUI specification files may be written using XMLmind XML Editor or using a text editor.
If you use a text editor, do not forget to validate your GUI specification against its schema. After downloading and installing the add-on called "XMLmind XML Editor Configuration Pack" using
. Linux example:
~/.xxe8/addon$ /opt/xxe/bin/xmltool validate \ -s ~/.xxe8/addon/xxe_config_pack/gui/xsd/gui.xsd customize.xxe_gui
 You'll need to download and install the add-on called "XMLmind XML Editor Configuration Pack" in order to do that.