There seems to be some confusion here. I'll start from some basic points just to (try to) be clear. Chris Cunnington's advice is a good place to start btw.

Scratch is written in Squeak Smalltalk, starting from a 2.8 image and removing quite a lot of code to reduce the image size. The Scratch system is implemented via a sort-of simulation of a computing engine, almost like a vm within the Squeak system.

Quite a lot of that code is a bit… untidy. I'm currently working to improve that for the Raspberry Pi Foundation and the latest release for the Pi (the image will run perfectly well on any other platform so far as I can tell) is around twice as fast for some important large Scratch projects. We also have a faster bitblt in testing right now, with a lot of ARM support but a fair bit that is generic and might benefit other cpu powered machines.

The delivered Scratch image is moderately locked down. As mentioned by Hannes, you can get to the Squeak side of the world with a simple shift-click but since there is no conncetion to the sources or changes files you won't have a terribly pleasnat time trying to make sense of the world. To see actual sources - with some comments even! - I suggest downloading the GPL release of the entire system that includes an image with the sources and changes still active, plus a load of media files to play with etc. 

(Except that I can't find the download place anymore, since they seem to have replaced the entire website to support this newfangled Scratch 2.0 written in Flash (Flash! Of all things…). Does anyone knw where the GPL release has gone to? I see the http://scratch.mit.edu/scratch_1.4/ page but that only appears to have 'end user' packages.)

Anyway, Azka, you will need to become conversant with all the normal coding tools in Squeak in order to make sense of any of it. The first confusion you seem to have picked up is that editing the sources file is a good idea; it's not. You never, ever, edit that file with any sort of text editor. Smalltalk is not some quaint textfile based compiler system. The only way to change the code is to use the tools in the image; the code browsers etc.



tim
--
tim Rowledge; tim at rowledge.org; http://www.rowledge.org/tim
Change is inevitable....except from vending machines.