Where to get graphical assets for UI and documentation
This page should help to find locations with icons, patterns, and other graphical assets of universal use in various repositories in Qt, Qt Creator, and other open-source projects. A quick search for all PNG files in the Qt6 repo returns more than 11K. This large number tells that it is close to impossible to find something you need quickly, but it also tells that some useful assets might be around the corner and you do not need to remake them.
Not all graphical assets are generic. Screenshots from an example are probably too specific for that example, whereas icons on the buttons in Qt Creator might be used for other purposes, for example.
Please note that graphical assets are covered by the same licensing terms as the source code of a module or a component in which you find them.
This page does not give a full and final overview. It is as detailed as much YOU contribute to it ;-)
Icons used in the Form Editor are located in: <repo>/qttools/src/designer/src/components/formeditor/images/widgets/