0. Have to use M$ Windows
Don't bother writing "M$", that is so last century.
way out: Use Cygwin.
In what way is that a way out? You will still be using Windows...
You should be aware that if you use Cygwin, and your intent is to
build software for "native" Windows (software that doesn't use the
Unix emulation that Cygwin provides), you must be very careful to
avoid confusion. I really suggest using MSYS instead. (Distributed
from the same site as MinGW.)
You should think of Cygwin as a completely separate operating system,
that just happens to run on top of Windows.
2. After downloading the code, I am not able to figure out the dependencies
(on Cygwin)
Even if you do insist on using Cygwin as you interactive shell
environment, don't look for dependencies "on Cygwin". If you for
instance use GTK+ for Cygwin it will require the X window system at
run-time, as far as I know. If you use a Cygwin build of libjpeg or
libpng, for instance, but GTK+ for Windows, you will justl be creating
an awful mess for yourself.
So, is there any way for Cygwin (for compiling GIMP from source), other than
manually going through each dependency and installing them (which I dont
know if will work in Cygwin or not)?
Well, let's forget Cygwin for now, right? But still, indeed, you need
to manually install suitable run-time and developer packages for the
dependencies for Windows. Most importantly, the GTK+ stack, and
libraries like libjpeg and libpng.
http://www.gtk.org/download-windows.html will help you a bit. And you
will have to build babl and gegl.
I hope I don't "have" to switch Linux for this.
Most people think it is easier to cross-compile GIMP for Windows from Linux.
--tml