tharpa said:
I'm a vb.net programmer, so this may seem like a dumb question to a classic vb'er.  But the function 

GetLastInputInfo is completely empty, i.e.

Private Shared Function GetLastInputInfo(ByRef plii As LASTINPUTINFO) As Boolean

End Function

What is the purpose of an empty function? 

It's not an empty function.... you'll notice it starts with <DllImport("User32.dll")> _

That signifies that the function exists in User32.dll.