The Quickbars are the compact controls at the sides of the workspace. They keep frequently used Explorer and Inspector actions available while leaving more room for the 3D Workspace.
In general, the purpose of the Quickbars is to free up space for 3D visualization while providing direct access to important features without opening the Explorer or Inspector. This is especially useful on mobile devices such as tablets.
The left Quickbar provides access to Explorer controls and sections. The right Quickbar provides fixed and context-specific Inspector controls for the selected item. Use the arrow at the top of either Quickbar to expand or collapse its panel.
When you load a space through the load-space Quickbar panel, the panel closes automatically after loading finishes.

The Inspector Quickbar with access to Blocks.
See also: Explorer, Inspector, and Main GUI Elements.