Donald Trump's opining about riots should he not get the nomination have prompted people to hearken back to the Democratic Convention of 1968. Why? Except for the implication of violence, your guess is as good as mine.
The demonstrators in '68 were mostly young anti-war protesters. They were serious about politics and peace. Trump supporters are comic in their politics looking like a combination of the elderly, Jerry Springer neo-nazis, and white trash. And they want anything but peace.
Yes, Springer/Trump is shot in the end.
Is Trump shooting himself in the foot?
He seems to do it constantly - at least to reasoning people. His insulting rhetoric comes close to offending even his most ardent supporters: for example, he dared to mess with FOX's old man eye candy Megyn Kelly (she is, after all, smart, straightforward and boob-a-licious).
Someone has posited that the entire Trump campaign is a joke - by Trump himself. If it is, it is a sick joke, magnifying America's love affair with stupidity. Sick, but alas, accurate in some ways: the reasons people give their support to Trump are vacuous in the extreme: "he tells it like it is" and "he's refreshingly blunt" are not reasons to vote man into the office of President. There is as little substance to their reasoning as there is in Trump's campaign.
1968 It's Not
If there are riots in Cleveland during the RNC, it will look as if the 1968 were turned inside out, backwards, and reverse: The Democratic Party, was in chaos, the protesters were peace-loving students (except, possibly, the Black Panthers), the violence was brought about by the police. There was not a white sheet or swastica to be seen. The Trump figure was the Democratic Mayor of Chicago, Richard J. Daley.
The only similarity between the two political conventions: Daley, like Trump, was the comic ringleader: when interviewed by Walter Cronkite, Daley appeared so bumbling, that Cronkite ended it with: "Well, I suppose this was to be a meeting of the minds - but it certainly wasn't". Check out the statement of Daley charging the Chicago PD to "preserve disorder"