Sorry I don't understand what Ub Iwerks mean.

@Jolanta Ubbe Ert Iwwerks, professionally known as Ub Iwerks was the partner of the Disney brothers and their chief animator, he was the creator of Mickey mouse and most of the other early popular characters.
When Walt declared the original company bankrupt he stole the copyright on all of the characters out from under Ub and his brother. He then started a new company in his own own name Disney pictures, and hired his brother to work with him, Ub on the other hand was given the character of "Oswald the Lucky Rabbit" and in effect told to go away.
Ub tried to start his own company but Disney crushed them and then used a hostile buy out to shut them down, in 1940 offering UB a job as a animation special effects supervisor on the condition he signed a non disclosure agreement, that in effect gagged him.
Ub died penniless in 1971, and in 1980 his granddaughter collaborated on a book exposing how her grand father was treated by "Uncle Walt" denying him even the right to speak out when Ub won two academy awards when he invented the multihead optical printer, used to combine live action and animation in films for Technical Achievement in 1960. he won a second Academy Award in 1965, the wetgate printer and the 360-degree motion picture screen, meaning he practically invented Imax, but for both inventions Disney held the licencing rights.

@LenHazell53 Thank you for all the information. I just red about him in Wikipedia and turns out that he was not such a nice man.

I think the kicking in the mouth is a bit more specific.

@Jolanta Actually I could for several pages, but that was enough.