The FileDialog in the QtQuick.Dialogs package has a property fileUrl containing the selected file by the user. On Windows the property has a value of file:///... and on linux file://.... So you have to handle this different on different operation systems, but this is not documented anywhere. A note saying that the 'prefix' is different on windows and linux would be cool.

I see that there are the functions pathToUrl and urlToPath which do the right thing, but they are not documented!
A documentation for the function addSelection would also be nice.