What you describe is custom javascript territory. It can be done, and I think others have posted their code here before. I am not saying that it can’t be done, but not as a plugin feature, as there is no generic solution. If you look at the code on the dropdown for that site in the code inspector for your browser, you will see that they have written custom javascript and attached it to the form control. Great if you are a coder, not so great otherwise.
There are plenty of suggested solutions to do this type of thing on stackexchange, but they need customizing. This is why we built the plugin to do this type of behavior but in a non-programmtic way, to make it easier, in general, to implement.