How can I look up the current/default guifont reliably?

Question

I'm trying to configure my guifont and I'd like to see the current setting so I can e.g. keep the same font but change the size. Is there a way to check the current font that works reliably, even if no font has been selected in the current vim session?

A similar question was previously asked on mailing lists at http://vim.1045645.n5.nabble.com/How-to-determine-current-font-in-use-td1181670.html but not sufficiently answered; set guifont only seems to get the current font if it's been explicitly set in the current vim session.

Answer 1

So it looks like if no guifont is specified in your vimrc, gVim will use some built in default font and it would not be reflected in guifont -- set guifont is empty.

But it turns out it is possible to change the size of your default font -- use guifont without name, just size:

set guifont=:h10
set guifont=:h16
...
whatever your default bitmap font supports