What compiler is used to build GTK+ Windows packages?

[Alexander Shaduri <ashaduri gmail com>]

Hello,

I'd like to know which version of mingw (gcc), binutils, w32api and
mingw-runtime were used when compiling the win32 packages of GTK+
located here:
http://www.gtk.org/download-windows.html

Also, are there any plans to use the mingw64 toolchain (like at
http://download.opensuse.org/repositories/windows:/mingw:/win32/ )?
Maybe for GTK+ 3?

Are there any plans to make the non-experimental (that is, backwards
binary-compatible) releases of win64 packages?
http://www.gtk.org/download-windows-64bit.html
What toolchain is used to build that and which version?

Thanks a lot in advance,
Alexander