If I want to create a window that is not a main application window (like say I want a Preferences window to pop up when a preferences menu has been clicked in the main window), how would I accomplish this?
"Any QWidget without a parent will be in it's own window." http://doc.qt.io/qt-4.8/qwidget.html
I recommemd to read about window-related functions and properties of QWidget. For preference window windowModality, windowType, windowFlags may be useful.