Oh I get it.
http://devnet.kentico.com/docs/webparts/index.html?Link_overview.htmUnder
Action, it has a
raise event property. The field is a dropdown offering only three choices: Submit, Next, Previous, and it's defaulted to Submit.
There's two tiny words I missed: "
If set, the action raises the postback..." So if it can be
set, then logically it can be
unset!
But, it is not at all apparent that you can ignore the dropdown,
erase the existing text (that says Submit), and leave the field
empty.
Veeeeery sneaky Kentico...