Document Type Editor

I must miss something here. When I created an empty document type, the toolbar in Document Type Editor was gray out. I was not able to add new fields into that empty document created.

Based on the document, it seems to pretty easy to add a field in document type editor.

I am using Developer Version 6.1 (132) in Windows XP sp2. the Help says "Note: To activate the toolbar buttons, click anywhere in the whitespace inside the editor. " It did not work for me.

What do I miss and how to enable the toolbar in Document Type Editor?