configurationgtk
In previous versions of gtk it was easy to launch one instance of an application with default gtk settings:
GTK2_RC_FILES= epdfview
But for version 3, it won't work anymore:
GTK3_RC_FILES= evince
has no effect. Is this convenience definitely gone?
Give xdotool (Ubuntu man page) a look.
It's extremely powerful and should be able to do whatever you need.
how can I choose the GTK engine used by Cinnamon to make my new desktop pretty?
WRT GTK 2: Try installing gtk-chtheme. This is an independent application:
I don't use Cinnamon (or Mint) but this has never failed to override a DE's settings for me.
These settings are (I presume) universally kept in ~/.gtkrc-2.0, but being able to browse the themes graphically makes things a little simpler.
Best Answer
Ok the implementation has changed and details can be found in the documentation for the GtkCssProvider class. To use plain default settings, one can now use following: