For the c++ api dox this expands to "\c nullptr" (the
\c directive indicates a code literal value), and for sipify/Python
it expands to ``None`` (`` is sphinx annotation for literal values)
Makes for nicer dox for both c++ and Python!
layout designer interface API
This commit adds more methods to the public, stable API for the layout
designer dialog, allowing plugins and scripts greater flexibility
in extending and hooking into the layout designer.
New API includes:
- access to the main menus shown in the dialog, allowing custom actions
to be added to the dialog
- access to the dialog's toolbars
- methods for adding (and removing) additional dock widgets to the designer
- the method used to show/hide rulers in the designer
otherwise if you access the config of the filter (or change app settings) from outside the main application settings dialog, results are not invalidate
for instance, if you update a URL of a service, results won't be updated
