The default behaviour of the Quartz window manager from the Apple X server 1.0 release is to require you to click on each window before you can type to it or press buttons.Sparky is a graphical program for doing NMR assignment and integration.It runs under Microsoft Windows, Linux, Mac OS X, and SGI, Sun, and HP/Tru64 flavors of Unix.It is by default set to "auto" and you should choose some number instead. I have not been able to test it because I have only Windows NT available and it does not exhibit this problem.
I don't know how big the number has to be -- just experiment or choose the biggest value in the pull down menu of choices. You may wish to examine platform specific installation notes for Linux or SGI.
This behaviour results from Sparky being an X windows application instead of a native Aqua application. The delete key on some Macs produces a backspace character when using an X windows program. Two X windows preference settings help avoid extra mouse clicks when using Sparky dialogs.