[winswitch] Tiny fonts with xpra 0.15.0

[Douglas Doole]

I just upgraded my xpra server to 0.15.0 and restarted xpra. Now when I
open up text windows (konsole, gvim) the font is so small that it's
illegible. (The client is running 0.15.0, but I didn't see this problem
with the 0.15.0 client and 0.14.25 server. It was only after the server
upgrade that the problem appeared.)

I'm guessing that the DPI information is messed up. Is this a bug, or had I
simply been getting away with a bad setting? If it's a bad setting, what am
I missing?