How to self-check for visual style in ..VB6

I've added Visual Styles (XP/Vista/W7 theme) support to a bunch of old vb6 apps. I've done this with a .manifest file and some other code, but I needed to check if visual styles are enabled. Without reading the manifest, of course. Here is the code I used to implement a IsThisTemed() function to tell if the running app has visual styles enabled. It is an adaptation of the vb.net code found here.

Private Type DLLVERSIONINFO
   cbSize As Long
   dwMajorVersion As Long
   dwMinorVersion As Long
   dwBuildNumber As Long
   dwPlatformId As Long
End Type

 Private Declare Function GetThemeSysSize Lib "uxTheme" ( _
   ByVal hTheme As Long, _
   ByVal iSizeId As Long) As Long
   
Private Declare Function GetVersionExA Lib "kernel32" _
               (lpVersionInformation As OSVERSIONINFO) As Integer
  
Private Type OSVERSIONINFO
  dwOSVersionInfoSize As Long
  dwMajorVersion As Long
  dwMinorVersion As Long
  dwBuildNumber As Long
  dwPlatformId As Long
  szCSDVersion As String * 128
End Type

Public Const VER_PLATFORM_WIN32s = 0        ' Win32s on Windows 3.1
Public Const VER_PLATFORM_WIN32_WINDOWS = 1 ' Windows 95, Windows 98, or Windows Me
Public Const VER_PLATFORM_WIN32_NT = 2      ' Windows NT, Windows 2000, Windows XP, or Windows Server 2003 family.


Private Declare Function DllGetVersion Lib "comctl32.dll" (ByRef version As DLLVERSIONINFO) As Integer

 Function IsThisThemed() As Boolean

Dim OSInfo As OSVERSIONINFO
Dim retvalue As Integer
  
OSInfo.dwOSVersionInfoSize = 148
OSInfo.szCSDVersion = Space$(128)
retvalue = GetVersionExA(OSInfo)

If OSInfo.dwPlatformId = VER_PLATFORM_WIN32_NT Then

If (((OSInfo.dwMajorVersion = 5) And (OSInfo.dwMinorVersion >= 1)) Or (OSInfo.dwMajorVersion > 5)) Then


    Dim version As DLLVERSIONINFO

    version.cbSize = Len(version)

    If DllGetVersion(version) = 0 Then
      
      IsThisThemed = (version.dwMajorVersion > 5) And (IsThemeActive() = 1) And (IsAppThemed() = 1)
    Exit Function
    End If
End If
End If

   IsThisThemed = False

End Function