A QToolBar becomes partially visible, and the necessary QToolbuttons hidden, if the width of the QMainWindow cannot display the entire tool bar. A partially visible tool bar can be made visible by clicking on the extension button. If extended, and then made floating, the QToolButtons that were hidden will remain hidden once the mouse leaves the floated tool bar.

If a docked and extended QToolBar is floated, it should become entirely visible, and all QToolButtons should be available.