There was a bug in the code related to adding the extension.  At some point, the file dialog became "smarter" about what you were trying to save.  For example, if the editor was in "Free-Format Fortran" mode, it would default to setting that extension as the default when you select "Save As."  Likewise for fixed-format Fortran.  However, the code that would append the extensions was not updated when this change was made.  If you ever chose the default extension in the file dialog, it would never append the extension.  So yes, there was a bug.

The dedent was definitely broken for a single line if you simply pressed Shift+Tab.  If you used the menu, though, it worked.  There was a bug in the editor code where the keystroke was interpreted that had to be fixed, and it seems to work now.  It will all be out in 3.13 in a week or so once we hunt down a handful of other bugs and confirm the compiler upgrade is okay.

It appears dedent doesn't work if it's performed on one line, but seems to work fine on multiple lines.  Can you confirm that you see this behavior as well?

I'll look into dedent.  Not sure why that has broken.  I'm not sure Save As... appending the extension has ever worked.