Apple says in their Human Interface Guidelines:
Use a popover to display a small amount of information or features. As a popover disappears after the user uses it, limit the number of features that it contains to a few related tasks.
There are common usage patterns, depending on the position of the sidebar.
Left bars: often used for navigation
Again referring to the Human Interface Guidelines:
Consider using a sidebar to allow users to interact with file-based data without exposing it to the file system. Regarding the thoroughness of file management, a sidebar summarizes the files into elements and containers specific to the application. For example, iTunes allows users to browse and manage media files such as songs, podcasts, and movies with the help of libraries and playlists, without having to interact with the file system.
An example of a file browser:
Atom editor. This is a common model for IDEs
Right Sidebar: Often Called Inspector Panel
Inspector panels or property sheets are used when you want to review details, edit properties, but you do not want to isolate or explore a separate view.
This allows you to examine a potentially large amount of detailed information while keeping the context of the whole.
An example is Omnifocus, the application of task management:
Note that the left allows me to navigate my projects.
the Inspector panel allows me to review the details of my task (deadlines, notes and status).
Since a task is one of the aspects of a larger object (the project), I would lose the ability to continue analyzing and scrolling through the list of tasks if I was sent to a new screen every time.
These are used in content creation, often in the manipulation of complex objects and graphic editing.
They are also an example of many icons displayed without support text labels, often because of the space.
Since these applications are often used frequently and for long sessions, they are intended for experienced users.
Choose a tool in the left toolbar:
In Adobe Photoshop, users can either:
- Add an object to document (form, text, lines)
- To select or crop a region of the document
- Edit existing objects in the document (blur, dodge, etc.)
- Navigate (zoom, panoramic)