How do I show a console output/window in a forms application?

Perhaps this is over-simplistic...

Create a Windows Form project...

Then: Project Properties -> Application -> Output Type -> Console Application

Then can have Console and Forms running together, works for me

this one should work.

using System.Runtime.InteropServices;

private void Form1_Load(object sender, EventArgs e)
{
    AllocConsole();
}

[DllImport("kernel32.dll", SetLastError = true)]
[return: MarshalAs(UnmanagedType.Bool)]
static extern bool AllocConsole();