V1.41 seems to be buggy. (I haven't tried previous versions.) Creating a new project with just the code from post #2 and then clicking on the tabs, some tab icons disappear and then reappear, and then eventually the interface stops responding at all. I have attached a screenshot at the point the interface has become unresponsive and the 4th tab's icon has disappeared. And another screenshot showing tab 2's icon having been replaced with tab 1's icon.
View attachment 91011
View attachment 91013