User interfaces for presenting content items to users

A computer-implemented method for use with one or more processors;

• memory;
• and one or more programs stored in the memory and configured to be executed by the one or more processors, the method comprising
• within a user interface that comprises at least one of:
• a single window or a single tab of a web browser or an augmented reality environment or a virtual reality environment, displaying one or more graphical units, at least one of the graphical units visibly encompassing simultaneously three or more content items or controls including at least one content item and at least one control, the items of each of the graphical units being associated with a particular application,
• at least two of the graphical units and the content items or controls encompassed by each of the graphical units being displayed sometimes simultaneously in respective positions in a horizontal array within the user interface, the presence or position or both of each of the graphical units in the horizontal array being changeable independently of the presence or position or both of at least another of the graphical units in the horizontal array, and
• in response to a user invoking independently each of at least two of the content items or controls of one of the graphical units, at least sometimes adding two corresponding graphical units to the horizontal array.