When I create a new Qtquick qml project and modify a qml file in "Design" mode I see a limited number of Qt Quick Basic components under the window Library QML Types
(like Rectangle and Button)
When navigate to the folder /opt/QTSDK/QtCreator/lib/qtcreator/qtcomponents/
I see a lot more components like CheckBox or RadioButton
How I can use these / see these in Design mode?
I know this is a year old, but I was looking for an answer to this just today.
To use a Button, CheckBox, RadioButton and other convenient controls, you have to
at the top of your QML file.
[Qt Quick Documentation]