This property controls whether a separate desktop is used at all. I highly recommend that you leave this as returning true. Tests on the separate desktop are faster and safer. (There is no danger of keyboard or mouse input going to your own separate running applications.) However I have heard report of operating systems or environments where the separate desktop does not work. In that case there are 2 options. You can override this method from your test class to return false. Or you can set an environment variable called "UseHiddenDesktop" and set that to "false" Either will cause the tests to run on your original, standard desktop.
NUnitFormTest Class | NUnit.Extensions.Forms Namespace