The dashboard section is in process of implementation. You can navigate to Documents or Images only from
Content >> Images or Content >> Documents.
You can edit the Dashboard from Settings >> Backend pages and put a link to the Images and Docuements section by using ContentBlock control.
Manage also section is created by PagesDefinitions class and extending this section will require a new definition where you have to define a new SideBar. The base class is internal and it cannot be reused in custom implementations.
In the BETA 2 it is not possible to extend the pages section with a new columns. There is not implementation that allows you to do this from the configurations.
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