I don't remember using an IDE for writing code ever. I am allergic to such stuff. I prefer a text editors and command line compilers or interpreters. Earlier when I used to write C/C++ code on Linux, I used to write the Make file myself, on Windows I only code in Python since it doesn't require the IDE fuss. I think one of the main reasons that backs me off of writing mobile applications is that IDE's, Simulators and stuff like that are required there, let alone my natural hatred for Java.
Anyway, I normally use Notepad++ as my text editor on Windows, and one of its cool features is that it remembers the files you had open in your last sessions and opens them the next time you use the program. Think of it that same way Firefox remembers the tabs you had open the previous time you used it. It's cool, it makes life easier when working on a project consisting of many files, instead of opening each one of them every time, yet sometimes you find yourself having zillions of open files from unrelated projects. So here is some other alternative.
In Notepad++ you can save your current session into a file, hence you can have a session file for each project you are working on.
First of all, go to "Settings >> Preferences.." then un-check the "Remember current session ..." field and assign a file extension for your session files, I used ".npp" here, but you can invent any extension.
Now whenever you are on a project with many open files, go to "File >> Save Session" and save your session into a file with .npp as its extension, next time whenever you click on that file your previous session for that project will be open. Whenever you add or remove files to your project you can Save your session and overwrites your session file with those new updates.