Mathias Benedek

One minor point - If the FIRST line of the help is a useful one line description of your function, including reasonable keywords, then the function lookfor will be able to search for your code. In this case, the author has a blank comment line in the help as the first line. Then he has a good descriptive line. But this means that lookfor no longer works on this file. For example, if I removed that blank line, then the command "lookfor chess" finds this file.

Another issue of note - the author uses globals in the code. Yes, perhaps the code works. But just imagine that you have some other code that uses the global variables "turn" or "status". Yep - your code may possibly no longer run properly if you use this clock!

The point is that global variables are dangerous, and simply not necessary to pass information around. Better approaches to the problem might have been to use nested functions for the callbacks, or guidata, or even persistent variables. At the very least, use names that are less likely to step on something else!

As for the clock itself, I like it. Its a nice idea. The help seems reasonable, as is the code, except for the use of globals. I might have added internal comments to the code - they are invaluable for the future when you will want to debug your own code if a problem comes up, or if you want to modify your code to add a new capability.

One downside to this clock - while I'm no longer a speed chess player (and an old nickname of mine, "Father Time", indicates I never really was a speed chess player) there is a certain satisfaction to smashing down the button on a chess clock after a particularly good move or sequence of moves. Will you get that same feeling when you hit the space bar on your keyboard?