SharpSoft SandboxSharp

SharpSoft SandboxSharp is a simple and easy to use development environment.
Not only is it suitable for beginners, but it can be used for library testing where Visual Studio's complexity is more of a detriment than a benefit.
It also supports WinForms windowed applications, so GUI controls can be used.It also supports 3rd party tools, so you can efficiently upload a program to an FTP server, for example.