Currently NVDA can only be compiled with Microsoft Visual c++ 2012 update 3 or higher, or Microsoft Visual C++ 2013. We should support compiling with Microsoft Visual C++ 2015. This requires Scons 2.4.1 and multiple fixes to our source code as VC 2015 is much more pickier about casting truncation on 64 bit (specifically in regards to HWND and HANDLE).