This patch, complements the existing vbox layout with a hbox layout and
improves the response to dynamic dialog updates. The new version support
disappearing widgets and the reordering of widgets. Furthermore, this
patch ensures that the 'Widget::_layout' functions are executed after
updating a new version of the dialog.
The menu view generates a simple dialog of widgets and reports the
hovered element. It is meant to be embedded into applications that
require simple GUIs but don't want to deal with the pecularities of
a full-blown widget set.