Yes, the research showing that the average high iq individual is more successful than the average low individual, is as deep and broad as the ocean.

The argument you're making has often been made as "there are different kinds of genius". The research seems to have debunked this. Rather than seeing multiple ways to be a genius, we see some general intelligence ability that helps you no matter what you're trying to do.

In the case of our painter, if we're talking about Michaelangelo or something, he'd likely come out with an excellent IQ.

As an aside, IQ tests don't try to make you do math problems and the like, it's all pattern matching kinds of questions where you learn all of the necessary context in the test itself. Which makes sense right, it's trying to measure your ability to learn and generalize, not what you happen to know before you take the test.

They're not called that, but they do exist. I recently went through a full day's testing for issues relating to autism and a number of the tests related to ability to hold focus rather than skill, per se.

One I recall vividly was basically a page full of weird symbols and a "key" at the top mapping symbols to numbers. I had to go through the whole page converting the entire page and various elements of my performance (variance of speed, attention, etc.) were measured during the task. This does not really correlate to what I'd consider focus or "flow" during typical programming tasks, however, but it did try my patience! :-)

However you're defining focus I'm sure correlates pretty well with the personality trait conscientiousness. (IQ is the best single-variable predictor of nice things like life success, for various definitions of success, IQ + Conscientiousness predicts even better...)