Is there a recommended way to make rules that change based on the environment?
For example, I want to use sfm in the console (without X), with fim image viewer. In the console, having a rule with DontWait is awful since sfm will steal the keyboard input from fim. However in an X session it is not a problem at all.
So somehow I would like to define a rule logic based on the value of DISPLAY environment variable. If it is defined then the rule will have DontWait, otherwise it will have Wait.