Symptoms
A control button ("Save" for example) will not disable until the rule is done executing. For a complex rule sequence (or possibly other system factors) there may be enough time for the user to click the Save button twice and actually execute it twice before the rule finishes.
One other thing to consider would be updating the button and toolbar button controls documentation to let people know that clicking the button does not automatically disable it. When I found the issue the first thing I did was to check the documentation to see if this was listed under the considerations. I found no reference to the potential problem and I do not recall any mention of this in the training. My guess is there are numerous applications coded that are not handling the possibility of a double click of a button.
Diagnoses
So what we are looking for here is Feature Request to provide the designer (in the layout view in the Designer) the ability to select a checkbox that does something like "disable the button after click until the rule finishes". This would probably go under the general section of the properties pane, probably near the current "Visible" and "Enabled" checkbox options. The control could default to true because in most cases, I believe people would want the button rules to complete before a second click could execute. Better documentation needs to be included to explain the current possibility of a duplicate click save before the rule finishes - and appropriate documentation later if the new feature is added in the properties pane.
Resolution
A feature request has been logged.
As a current workaround it is possible to add a rule to disable the button after clicking it - and then another rule to re-enable it after the rule finishes. The proposed Feature Request would remove the need for these added rules.
