I wish to run a few notebooks (with distinct contexts) at once using MMA 10 on Windows 8.1. I wish to run at least one of the notebooks interactively, adding and executing lines of code. If another notebook needs attention, perhaps by opening a dialog box, I need to be able to open that window, respond, and then return to the notebook in which I was doing code development. How do I accomplish this?
You can use several Mathematica kernels for this purpose.
Go to Evalution -> Kernel Configuration Options. In this menu you can add new kernels.
After in notebook, you can specify which kernel it must use by Evaluation -> Notebook's kernel.
Usually, I use two local Mathematica kernels. When default one is doing some number crunching, in other notebook, which I want to run interactively, I use the other (not busy) kernel.