I recently set up custom content types for my standard templates so that everybody (in subsites) can benefit from it using the NEW button.
So far so good, all documents open, I only have 2 issues:
1) XLSB Files open Excel but with a popup message stating: "The file format and extension of "<documentname>.htm" don't match. The file could be corrupted or unsafe. Unless you trust its source, don't open it. Do you want to open it anyway? Don't know why it says this is a HTM file when I clearly reference an XLSB file...
2) a minor issue, but annoying nontheless. PPTX files are not created with the Document Title in mind, they are always loaded as "Presentation1". Can they be made to obey and read the title properly?
I'm afraid there is not a way to solve both issues: 1) I think the New button is expecting a xlsx, pptx, doccx extension type so as soon as you try another when it starts "complaining" with weird messages 2) No way to instruct Content Type configuration to read the title property for PPTX files