Write a C# Windows Forms App code in Visual studio with a "start", "stop", "up", "down", "left" and "right" buttons and a textbox.

The textbox should start printing numbers from 1 to 100 on the press of the "start" button and stop printing process immediately on the press of "stop" button.

Also create a thread after stop button is pressed to allow manual input from "up", "down", "left" and "right" buttons and print up, down, left or right in the same textbox.