what does ことに...ことに... mean here?

Question

この教室の窓というのが、トットちゃんにとっては幸福なことに、先生にとっては不幸なことに、一階にあり、しかも通りは目の前だった。

I googled it ,and it only turned out ことに used like this

残念なことに、その商品はもう販売中止になりました。

but this usage obviously don't match the context I provided

Answer 1

The Google phrase you looked up is exactly what is happening here. It sounds like トットちゃん is trying to escape the classroom.

This ことに attaches to some i-adjectives and na-adjectives and effectively adds the English suffix 'ly'.

In this case we have 幸福なことに = "happily" and 不幸なことに = "unhappily".

This classroom window, happily for Totto and unhappily for the teacher, was on the first floor and looked out onto the street.