<summary>Child process setup callback delegate.</summary>
<remarks>Pass this delegate one of the Spawn methods on <seecref="T:GLib.Process"/> to perform process setup. Note that using this capability can cause portability issues if you are targetting a win32 environment. In POSIX environments, the function is run in the child's environment, but on win32 this is not possible, so it runs in the parent environment.</remarks>