xpra gtk problems

[bencpeters]

I'm trying to get xpra up and running on 10.9.3. Homebrew installs xpra with no errors, but when I try to run it (e.g. xpra_launcher), I start to get gtk errors in my terminal. xpra_launcher's GUI does pop up, but it produces the first few lines of the error shown in the output below. However, when I enter the connection information and try to connect, I get the X Window System error shown below.

benpeters@Bens-Mac-mini.~ $ xpra_launcher
ERROR: gtkosx_application module is missing - trying to continue anyway
ERROR: gtkosx_application module is missing - trying to continue anyway
2014-06-13 10:34:08,108 OpenGL support not enabled: No module named OpenGL
ERROR: gtkosx_application module is missing - trying to continue anyway
ERROR: gtkosx_application module is missing - trying to continue anyway
ERROR: gtkosx_application module is missing - trying to continue anyway
ERROR: gtkosx_application module is missing - trying to continue anyway
ERROR: gtkosx_application module is missing - trying to continue anyway
The program 'Xpra-Launcher' received an X Window System error.
This probably reflects a bug in the program.
The error was 'BadDrawable (invalid Pixmap or Window parameter)'.
  (Details: serial 6273 error_code 9 request_code 128 minor_code 8)
  (Note to programmers: normally, X errors are reported asynchronously;
   that is, you will receive the error a while after causing it.
   To debug your program, run it with the --sync command line
   option to change this behavior. You can then get a meaningful
   backtrace from your debugger if you break on the gdk_x_error() function.)

Any ideas? Happy to give more configuration details, but I honestly am not really sure where to start debugging this error...