Yesterday night I tried out someone's project in progress and played with the skins a little (using 410.975). This morning I started up BYOND and went to try a project I'm working on. When I went to run it, I got a message that the skin has been updated (even though the project doesn't even have a Hub entry) and I declined it, but the game still wants to use skins, which just gives me a blank screen. (Then I tried creating a map skin, but I didn't get that right either.)

Since then I've tried creating and deleting an interface file, doing a clean compile, and even rebooting the computer, but I'm still getting this small blank window instead of the old BYOND behavior. What do I have to do to trick BYOND into using backward-compatibility mode?
Oops, looks like there's a more recent update that might fix this. I'll check it out.
In response to Gughunter (#1)
Almost sounds like it messed up your saved.txt file. It's located in the skins directory of your BYOND application data folder under BYOND. For me, on winXp, thats:

C:\Documents and Settings\User\Application Data\BYOND\Skins\BYOND

My saved.txt file, which should be the same as default, looks like:

<code> = "true" = "false" = "false" mainwindow.pos = "281,0" mainwindow.size = "640x440" = "false" mapwindow.pos = "0,0" mapwindow.size = "315x400" = "false" = "0" outputwindow.pos = "0,0" outputwindow.size = "315x400" = "false" outputwindow.output.max-lines = "1000" rpane.pos = "319,0" rpane.size = "315x400" = "false" rpane.rpanewindow.splitter = "50" mainwindow.mainvsplit.splitter = "50" = "false" </code>

In response to Xooxer (#2)
Ah, that's good to know. Thanks! In this case, installing the latest update fixed the problem -- it still runs in a small window instead of the old-style client, but it's fully functional. I'll try and keep saved.txt in mind for the future, though.