Note In order to keep my wiki up to date, I now embedded the most important sheets with the Iframe widget. Still convinced that Widget:Google Spreadsheet isn't working properly.
All the sudden my Widget:Google Spreadsheet (such as http://drebbel.net/wiki/Test:Nowadays) started to fail with a Refused to display 'https://spreadsheets.google.com/...' in a frame because it set 'X-Frame-Options' to 'SAMEORIGIN'. message. This is the sheet. (published and shared anyone with the link) Widget:Google Document however works fine ... Published everything the same way.
- Manual:$wgApiFrameOptions and similar
don't change anything.
My site is drebbel.net/wiki
Thanks in advance.