Comment 1 for bug 1334376

I think a better option would be to dismiss the dialog straight away, and either replace it with a full screen spinner, or a small spinner at the top like when a filter is being performed.

Greying out all the various form controls would be an alternative (just the submit button would still be inconsistent, though it should prevent the double submit issue - unless it is possible to press enter in a text field and still submit, even if the submit button itself is greyed out? i.e. safer to get rid of the form!)