How to do the screen cast in Linux
See http://askubuntu.com/questions/107726/how-to-create-animated-gif-images-of-a-screencast.
Issues:
- does not work in i3.
- I'd better put all the files in ram disk because it takes time for the conversion
- gifsicle is NOT needed
- I need find some way to adjust the record frame
- I use gimp to crop the gif