I think a lot of us assumed that Robert Young had taken a few years off in between Father Knows Best and Marcus Welby, MD, but in truth, he had tried out one more sitcom in between, and it didn't work.
Actually, Window on Main Street is classified as a comedy-drama, or, in the modern parlance, a dramedy, as there's little in the way of a laugh track. Young plays widower-author Cameron Garrett Brooks, who is still getting over the death of his wife, which was touched on in the Christmas episode, "Christmas Memory", which we'll get to later on.
Window, like Father, also boasted Young as one of its producers through his production company, which this time leased out some space at Desilu to film the show (Father Knows Best is otherwise a Screen Gems production). The series lasted just 1 season, which might've been enough to convince Young that it was time to change gears, leading to Welby, a medical drama, a few years later.
Gilmore Box supplies the open:
And here's "Christmas Memory", courtesy of Internet Archive:
Except for its inclusion on Shout! Factory's Merry Sitcom Christmas compilation DVD, I had not heard of this show beforehand.
Rating (based on the Christmas episode): B.