static extern IntPtr GetActiveWindow();

Declare Function GetActiveWindow Lib "coredll.dll" () As IntPtr

        hWnd= GetActiveWindow();

static extern IntPtr GetActiveWindow();

Private Shared Function GetActiveWindow() As IntPtr

Public Declare Function GetActiveWindow Lib "user32.dll" () As Long

if (GetActiveWindow() == Handle) {

        var windowHandler = GetActiveWindowHandle();

Then use winHelp.Handle insted of GetActiveWindowHandle().

            GetActiveWindow(),