It was John that / who was talking to her.

I have learned about it that cleft sentence, using this example below,

It was John that / who broke the window.

So I am not familiar with progressive tense like

It was John that / who was talking to her.

So my question is that we can consider it as a it that cleft sentence, used with progressive tense or it is an example of relative clause sentences and relative pronouns such as who, that, which, etc + be are usually omitted?

What do you native English speakers think? Thank you so much as usual in advance!

I am sorry about not being smart about this.