This is the best I could come up with, I inserted a commandbutton called commanbutton1, change this in the code to whatever the name of your button is:
<pre>
Private Sub CommandButton1_MouseMove(ByVal Button As Integer, ByVal Shift As Integer, ByVal X As Single, ByVal Y As Single)
' Dim iColour As Long
With CommandButton1
'
' iColour = &H0&
.ForeColor = &HFF&
If X < 5 _
Or X > .Width - 5 _
Or Y < 5 _
Or Y > .Height - 5 Then
.ForeColor = &H0& 'Assume font colour is originally black
Exit Sub
Else
End If
End With
End Sub</pre>
The drawbacks are that if you move the mouse away very quickly, the text will stay red, I used the value 5 to make the box smaller in terms of the colour changing to try to reduce this fast mouse move.
HTH
Oh yeah, to insert the code, rightclick on the name tab of the sheet that holds the button and select "View Code", copy and paste this code into the window and change "CommandButton1" to the name of your button, there are only two places in the code where you need to do this.