Grazie giano118 ma ho fatto questo script e mi funziona:

Private Sub Toolbar1_ButtonClick(ByVal Button As MSComCtlLib.Button)
On Error Resume Next
Select Case Button.Key
Case "Bold"
For Each Controllo In Form1.Controls
If TypeOf Controllo Is TextBox Then
Controllo.FontBold = True
End If
Next Controllo
Case "Italic"
For Each Controllo In Form1.Controls
If TypeOf Controllo Is TextBox Then
Controllo.FontItalic = True
End If
Next Controllo
Case "Strike Through"
For Each Controllo In Form1.Controls
If TypeOf Controllo Is TextBox Then
Controllo.FontStrikethru = True
End If
Next Controllo
Case "Underline"
For Each Controllo In Form1.Controls
If TypeOf Controllo Is TextBox Then
Controllo.FontUnderline = True
End If
Next Controllo
Case "Undo"
For Each Controllo In Form1.Controls
If TypeOf Controllo Is TextBox Then
Controllo.FontStrikethru = False
Controllo.FontUnderline = False
Controllo.FontItalic = False
Controllo.FontBold = False
End If
Next Controllo
End Select
End Sub


Provalo...Ciao