How to tell what document class is in use?

[terrypin]

This question arises out of my attempt to change printing fonts (my post a few minutes ago) but thought I'd better make it a separate post.

I'm getting in something of a mess because I've never really understood how document classes work. For example although my Default class is apparently associated with every file type (*.*), when I occasionally view some types (e.g. .INO, an Arduino sketch file), it uses the appropriate syntax and colours.

Also, I'm getting a message the 'No default printer is set', which is incorrect, as my Canon Pixma is shown in Win 10 settings as the default.

[Smelter.uk]

I was searching for document class info for Arduino sketch colour highlighting and found your post. You don't actually say what your question is, it simply reads as a series of statements, which is probably why you have no answers.
However you have answered my question I was about to post as to does TextPad recognise .ino files and do the appropriate colour scheme.

So thanks for your post. But as to your question?

[bbadmin]

Right click the document, choose Properties, and its class is shown at the bottom of the Document page.