I used to have a problem with readjusting window sizes and positions between the laptop and my 24" display until I discovered full-screen apps in the recent OS X. Now I just run the text editor full-scren on both
I am a big fan of being able to just work whenever I want on my computer... but I also am extremely big fan of plugging it to external displays and use ergonomic devices, and I try to use them as much as I can. At my office I use a Kinesis Freestyle and a trackball, and am very happy since I started using it. We spend so much time in these "positions" that we should minimize possibilities of having problems and be confortable... at the end we want to keep doing this for long time ;)