FolderBrowserDialog opening behind active application

Calling the Thread.....
=========================

<stathread()> _
Shared Sub Main()

End Sub


Code behind for button click event;.......
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Protected Sub button_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles button.Click
dr = New DialogResult()
folderBrowserDialog1 = New System.Windows.Forms.FolderBrowserDialog()
InpfolderPath = STAShowDialog(folderBrowserDialog1)
If Not (InpfolderPath = "") Then
txtInpFilePath.Text = InpfolderPath
End If
End Sub


Calling the method STAShowDialog...
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Private Function STAShowDialog(ByVal FD As FolderBrowserDialog) As String
Dim obj As cls_FolderDialog = New cls_FolderDialog
obj.fd = FD
Dim t As System.Threading.Thread = New System.Threading.Thread(AddressOf obj.FolderDialog)
t.SetApartmentState(System.Threading.ApartmentState.STA)
t.Start()
t.Join()
Return obj.strfilename
End Function


Class cls_FolderDialog...
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Public Function FolderDialog() As String
DialogResult1 = New DialogResult
fd = New FolderBrowserDialog
fd.ShowNewFolderButton = "False"
fd.Description = "Select Input Folder"
DialogResult1 = fd.ShowDialog()
strfilename = fd.SelectedPath
Return strfilename
End Function