You could change the caption of the appropriate button when the tab is selected from "Update" to "&Update", and change all the other button caption's to "Update"
For example, if you have all 3 buttons in a control array cmdUpdate (cmdUpdate(0), cmdUpdate(1) etc.), you could do something like this:
Code:
cmbUpdate(0).Caption = "Update"
cmbUpdate(1).Caption = "Update"
cmbUpdate(2).Caption = "Update"
cmdUpdate(TabSelected).Caption = "&Update"
I hope that helps.
Regards
Owain Williams