Never, during the peace talks… because, obviously, such a demand was counter to the notion of the peace talks. It was generally a position held by groups like the PLO, prior to the talks.
A more recent example would be when hostilities resumed in 2006, after Hamas won parlimentary elections amongst the Palestinians, and refused to renounce their goal of destruction of Israel.
Israel recently (as in, within the past month recently) shifted the goal posts to “agree that Israel has a right to exist as a Jewish state”. The Palestinians won’t do this, a) because it effectively dispenses with the Right of Return, which still needs to be negotiated (and which everyone off the record agrees will be a financial compensation as few Palestinian refugees actually want to live in Tel Aviv) and b) because Israel has a sizeable non-Jewish Palestinian minority of Israeli citizens, and the Palestinians don’t care to be complicit in their disenfranchisement.
Israel, since its inception, has existed as essentially a Jewish state. That is, it was specifically created as a homeland for the jews after WWII.
This tends to be a difficult topic to discuss, because it goes against some key element of western thought. Despite most Americans being Christian, for instance, most Americans don’t really think of America as a “Christian state”.
At the same time, it’s difficult to separate it from Israel’s identity, due to the reasons it was created, and their national identity. Hell, they have the star of David on their flag.
I don’t think the “Right of Return” is really going to pan out in such negotiations. Most of the Palestinians who once lived in Israel prior to its creation are dead now. The Israelis who live there now have lived there for generations.
I don’t see it as happening, but instead it could serve as a basis for some kind of reparations.
Ultimately, it’s just dirt. It seems like it’d be better to live on their current patch of dirt in a peaceful situation where they can build something of value, rather than always fight for some other patch of dirt that their ancestors once lived on.