Yeah I can imagine doing that all right - I wouldn't actually mind writing in latex even, the problem is the lag. Building a latex document after each change takes time. If the latex was being built in a window next to it, in real time, (say a 1 second lag would probably be fine) there'd be no problem. I'm not looking to publish the math, I just want a thought-aid.
I believe that there is an editor called lyx that lets you do this.
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