@Pythonic-person said in Widgets with SizePolicy there is no effects:
Do you mean taking the main window size and then change the widget size with the code?
You either use one of the provided layout mechanisms, develop you your only layout implementation, or you do all the resizing of contained widgets yourself 1990's style.
If you wish to do it yourself then you need to override the resizeEvent() of the container widget and resize the contained widgets yourself using whatever logic you see fit.