Better head content management

The window for the custom code in the head content shows only 4 lines. With custom JS and whatnot it's quickly a pain to scroll through it in such a small window. I don't see a reason why it couldn't be at least as high as the properties modal. The the same window in the settings is higher, but still shows too little to troubleshoot quickly. I think nobody would object getting more screen real estate in both cases :)