How to disable the submit button in opera mini to prevent multiple submissions of a form

Question

Because Opera mini only fires button events on Opera's servers when a form is finally submitted, I am having trouble preventing users from multiclicking the submit button. This results in multiple submissions of the same form. I could prevent this server-side, but is there any way to prevent this on the opera mini client (i.e. via javascript)?

Essentially,

1. The user is clicking submit
2. Before the form is processed and any javascript attempting to prevent multiple submission is executed on Opera's servers, the user is clicking submit again.