Behavior of the mouse in general, and the naming of the buttons is covered in the chapter on the overall user interface (see Chapter 8, Introduction).
This action is generally used to select an item for subsequent operations.
Within the hierarchical display, elements which have sub-hierarchies may be indicated by when the hierarchy is hidden and when the hierarchy is open.
When these icons are displayed, the display of the hierarchy is toggled by button 1 click on these icons.
Button 1 click over the headline of any to-do item will
cause its details to be shown in the
To Do Item tab of the details pane. That tab is
automatically selected if it is not currently visible.
When applied to the folder icon alongside a hierarchy category, this will cause the display of that hierarchy to be toggled.
When applied to a headline, button 1 double click will show the diagram for the model element to which the to-do item applies in the editing pane and select the model element on the diagram using an appropriate clarifier (the model element may be highlighted, underlined with a wavy line or surrounded by a colored box as appropriate).