VBA to check if user has pdf file open

Hello Rerock,

Here is the 64 bit version of the macro.

' 64 Fit Windows API Calls.
Private Declare PtrSafe Function FindWindow Lib "user32.dll" Alias "FindWindowA" (ByVal lpClassName As String, ByVal lpWindowName As String) As LongPtr

Private Declare PtrSafe Function GetClassName Lib "user32.dll" Alias "GetClassNameA" (ByVal hwnd As LongPtr, ByVal lpClassName As String, ByVal nMaxCount As Long) As Long

Private Declare PtrSafe Function GetNextWindow Lib "user32.dll" Alias "GetWindow" (ByVal hwnd As LongPtr, ByVal wFlag As Long) As LongPtr

Private Declare PtrSafe Function SendMessage Lib "user32.dll" Alias "SendMessageA" (ByVal hwnd As LongPtr, ByVal wMsg As Long, ByVal wParam As LongPtr, lParam As Any) As LongPtr


Sub ClosePDF(ByVal FileName As String)

    Dim Found   As Boolean
    Dim hwnd    As LongPtr
    Dim RefCell As Range
    Dim ret     As LongPtr
    Dim Title   As String
    Dim WndCls  As String
    
    Const GW_HWNDNEXT   As Long = 2
    Const WM_CLOSE      As Long = 16
    
       If FileName = "" Then Exit Sub
       
        hwnd = FindWindow(vbNullString, vbNullString)

        Do Until hwnd = 0
            WndCls = String(512, Chr(0))
            ret = GetClassName(hwnd, WndCls, 512)
                If Left(WndCls, ret) = "AcrobatSDIWindow" Then
                    Title = String(512, Chr(0))
                    ret = GetWindowText(hwnd, Title, Len(Title))
                    If InStr(1, Title, FileName, vbTextCompare) Then
                        ret = SendMessage(hwnd, WM_CLOSE, 0, ByVal 0)
                        Found = True
                        Exit Do
                    End If
                End If
            hwnd = GetWindow(hwnd, GW_HWNDNEXT)
        Loop
  
        If Not Found Then MsgBox "The Following PDF Document Was Not Found :" & vbCrLf & vbCrLf & FileName
        
End Sub