Deckard and LibreOffice

LibreOffice reuses the same ui format that gtk uses. This suggests that deckard could be used to preview translations of them.

Testing this out shows (as above) that it can be made to work. A few problems though:

1. We have various placeholder widgets which don't work in deckard because the widgets don't exist in gtk so dialogs that use them can't display as something falls over with e.g. "Invalid object type 'SvSimpleTableContainer'" I had hoped I'd get placeholders by default on failure.
2. Our .po translation entries for the dialogs strings all have autogenerated msgctxt fields which don't correspond to the blank default of the .ui so the msgctxt fields have to be removed, then msguniq to remove duplicates, and the result can the be run through msgfmt to create a .mo that works with deckard to show web-previews

Office Binary Document RC4 CryptoAPI Encryption

In LibreOffice we've long supported Microsoft Office's "Office Binary Document RC4 Encryption" for decrypting xls, doc and ppt. But somewhere along the line the Microsoft Office encryption scheme was replaced by a new one, "Office Binary Document RC4 CryptoAPI Encryption", which we didn't support. This is what the error dialog of...

"The encryption method used in this document is not supported. Only Microsoft Office 97/2000 compatible password encryption is supported."

...from LibreOffice is telling you when you open, for example, an encrypted xls saved by a contemporary Microsoft Excel version.

I got the newer scheme working this morning for xls, so from LibreOffice 5-3 onwards (I may backport to upstream 5-2 and Fedora 5-1) these variants can be successfully decrypted and viewed in LibreOffice.