[PyQt] QVBoxLayout default (minimum) size

[malonn]

In the app I'm working on, I set margins to 0. I was just doing some research; trying to see what's what. The window/application size tends to grow as you add layouts (and of course, widgets). You can reduce that by cuttings margins. I also found that Qt tends to choose the minimum size of the layouts when working with large widgets (such as large pixmaps). Naturally, it can all be bent to your needs, but that's the way Qt does it.