What happened to Hitler as a child in Vienna?

Nothing, Hitler did not move to Vienna until 1907, when he was 18.

In 1907 Hitler applied to the Vienna Academy of Art, and sat the entrance exam, along with 112 other candidates. He was subsequently invited to take part in the second round of the selection procedure, along with 79 other candidates but failed to qualify for a place.

Initially, Hitler was able to live quite well in Vienna off an orphan's pension and from the sale of paintings and post cards (his income was more that that of a primary school teacher). He returned briefly to his home town of Linz following news that his mother was dying of breast cancer and following her death on 21 December 1907, he distanced himself ever more from his relatives.

In 1908 Hitler reapplied for a place at the Vienna Academy of Art but this time failed to make it through the first round of the selection process.

During this time Hitler came into contact with the writings of Guido von List, a racial ideologist and antisemite, and his pupil Jörg Lanz von Liebenfels, as well as the antisemitic polemics of Austrian politicians Georg von Schönerer )leader of the Alldeutsche Bewegung (pan-German Movement) and the Mayor of Vienna, Karl Lueger. Hitler's concept of a superior Aryan, so-called master race probably began to form at this time. But according to his friend, August Kubizek, Hitler was more interested in Opera, especially Richard Wagner, at the time than politics

Whilst Hitler called his five years in Vienna "five years of hardship and misery" in his book "Mein Kampf", this version of events has been debunked by contemporary witnesses.

In their biograhies of Hitler, Alan Bullock and Ian Kershaw cite evidence that contradicts his version of his years in Vienna. 'Mein Kampf' is not a trustworthy source. It's a work of propaganda and essentially one long rant by a man with a grudge.