One rule of Alberta politics is pretty well absolute: visiting leaders get a friendly welcome in the legislature, whether the welcomers mean it or not.

That genteel convention collapsed Thursday, when Wildrose gave Ontario Liberal Premier Kathleen Wynne a greeting that wasn’t just frigid, but openly hostile.

Most of the Wildrose caucus didn’t stand to applaud after Notley introduced Wynne. Wildrose Leader Brian Jean stayed in his seat.

That was startling. What followed was shocking.

“You are so tacky.”

Wildrose MLA Derek Fildebrandt excoriated both Ontario’s debt and the province’s emissions plan.

“For power consumers, it’s meant skyrocketing power bills, massive subsidies to unprofitable initiatives, and auditor general reports into billions of wasted tax dollars,” Fildebrandt thundered.

“A few months ago our premier praised the Ontario plan. Is the premier still endorsing this plan, and if so, what part does she think will benefit Albertans?”

He was doing his best to embarrass Notley and Wynne while the visitor looked on.

Now, many people may agree with the substance of what Fildebrandt said. But Wildrose was ignoring both common civility and the hospitality Albertans cherish, just to make points that could have waited until the visitor was back home.

Ontario, we should recall, was extremely generous during the Fort McMurray fire, sending firefighters, equipment and money. Wynne herself was helpful and sympathetic.

But there are moments when Alberta seems to be heading for Trumpism, the derision of any compromise in politics, the flat out attack on the enemy, the refusal to acknowledge that anybody else has good intentions.

The reactions Thursday were certainly familiar to anybody who’s following U.S. politics.

One person said on Twitter: “WR magnificent in ABleg today. Citizens at war with corrupt government out to destroy our country.”

Another said: “Deplorable way to treat a guest in our house of government. Shame.”

Government house leader Brian Mason turned to Fildebrandt and said, “You are so tacky.”

It’s the Trump split in a few sentences; wild anger on one side, stunned disbelief on the other. This split is social, cultural and political — and increasingly disturbing all three ways.

And yet, Wynne is here with a message that at least sounds friendly to Alberta’s interests.

For starters, she says natural gas “is not being banned.”

Following the leak of an Ontario cabinet document on May 12, the province appeared to be heading for a complete shutdown of natural gas by 2030. After that date, no new home in Ontario would be allowed to have natural gas heating.