The awesome thing about Crunchbang is that you can do almost anything :) In this case, I was looking for a way to invert screen colors in #!, similar to what I had done earlier on Ubuntu w/Compiz Fusion. I searched around a little and found a nifty tool called xcalib. Here are the steps to having a key or two invert your screen.
1) Download the xcalib binary from the link above.
2) Save it somewhere you will be able to find later (like your home directory or a scripts directory if you have one).
3) Right-click on the file, go to Permissions, and check the little box at the bottom that will let you run the file as a program.
4) Copy and paste this code into the keyboard section of rc.xml (usually located at ~/.config/openbox/rc.xml):
<keybind key="W-i"> <action name="Execute"> <startupnotify> <enabled>true</enabled> <name>Invert Screen</name> </startupnotify> <command>/path/to/xcalib -i -a</command> </action> </keybind>
Make sure you replace
/path/to/xcalib with the real path!!
5) That's it! Simply reconfigure OpenBox and you can now invert your screen by pressing the Windows key and i together! (You can edit the shortcut itself by changing the first line's key= statement)