Then, another idea.
1. Copy text in textbox to the Visio.shape
2. Start spell ceck with DoCmd.
3. Chek and edit spell with dialogs.
4. Retrn text to TextBox.
My test code is
Private Sub CommandButton1_Click()
On Error Resume Next
ActivePage.Shapes(1).Text = TextBox1.Text
Application.DoCmd 1270
TextBox1.Text = ActivePage.Shapes(1).Text
End Sub