Don't block the UI thread when doing some expensive work. I'm using LINQPad at work and at home (ironically I paid for my home license but am using the unregistered version one at work) and at work I connect to large databases with thousands of tables and LINQPad takes a long time to "deal" with scripts connecting to these kinds of databases but it would help with a progress bar or at least some notion of "I'm busy" rather than the ghost whitening of the UI.
Otherwise thanks for a superb product. :-)
Piers Williams commented
If you call .ToObservable() on the enumerable that you are dumping you'll get progressively rendered output. You will have to reference rx-main nuget first of course.