As a long time user of vi/vim/gvim, I did not feel a huge push to explore all the tools mentionned by Niel Gershenfeld. I feel more confortable with command line tools than complex GUI... But sometimes I am lazy (or in a hurry ?).
Nevertheless, I had a look at Atom as text editor, and the whole chain including Electron as cross platform framework, and Photon for building GUI. It seems worthwile to make an effort to learn the whole set. It seamlessly integrates with Git.Electron allows HTML/Javascript/CSS web application developpment, but unlike Phonegap/Cordova it's not limited to mobile phones.