Right now, the button that opens the popup with the wizard to define the parameters of a template, only appears on the template namespace.
Usually, the template data is placed in the template itself, or a subpage transcluded on the template that is used as documentation for the template.
Problem: On our wiki, I decided it was a good idea to move the documentation template subpages into a new custom namespace, to avoid those subpages appear in link suggestions (Extension:LinkSuggest). However, this makes the button not appear in the documentation pages. This could be solved by adding a configuration parameter to set in which namespaces the template data button should appear.
I can "workaround" it by editing the template and using the button from there, or copy/paste the contents in a random template page.