Comment 22 for bug 274461

To be honest, gnome-terminal supports rgba too (well, the only non-console widget in gnome-terminal, i.e. the menubar)

For more info about reasons, status, and future or RGBA in gtk+ and Murrine, see also

  http://www.cimitan.com/blog/2007/12/12/gtk-rgba-transparent-widgets-with-the-murrine-engine/
  http://www.cimitan.com/blog/2008/02/17/rgba-colormap-by-default-in-gtk-call-for-a-coder/

About Ubuntu, the Artwork Team have to choose: enable RGBA in Human theme or not. If enabled, only applications supporting this feature will be semi-transient.

It's not a bug, it's not a feature. It's a cabapility of GTK+ libraries that applications and theme engines can use. Most probably GTK+ 3 will normalize the usage of this feature for all GNOME apps.

> In the mean time how can I re-enable transparency in the ubuntu theme? thanks

Open /usr/share/themes/Human/gtk-2.0/gtkrc , find "rgba" option and change its value from FALSE to TRUE.

Same for all other Murrine based themes.