Sheets need to be able to display the title of the document they are applied to

Document sheets control both how the content and the title of documents are displayed. If you want to include the content of the displayed document in the sheet you can use the include macro, like this:

before

{{include document="$doc.fullName"/}}

after

We need to be able to do the same with the document title. Right now, if you try to use $doc.getRenderedTitle() in a sheet you get infinite recursion because the same sheet will be applied over and over.