Comment 5 for bug 533520

Maybe there is another way to workaround it. Here [1] is the code related to the vino message box area widget. It seems the widget itself is named "gtk-tooltip".

GtkRc should allow you to (see [2]) to apply a custom style to a specific widget in a specific application. Something like the following should work.

  style "vino-message-area-fix"
  {
    ## insert here proper color
  }

  widget "vino.gtk-tooltip" style "vino-message-area-fix"

Of course it's totally untested and needs more investigation.

[1] http://pastebin.ubuntu.com/390461/
[2] http://live.gnome.org/GnomeArt/Tutorials/GtkThemes#widget_matches