In some toolboxes, such as the Views toolbox, all tool icons are immediately visible; however, most toolboxes contain hidden icons to conserve space. Any icon that includes a small triangle in its lower right corner conceals a group of icons whose function is closely related to that of the visible icon.
To select tools whose icons are initially hidden:
Click and hold any icon that includes a triangle in its lower right corner.
Icons for all the tools that are closely related to the original icon appear. For example, Figure 312 shows the top portion of the Part module toolbox with all of the icons revealed that are used for creating round or chamfered corners.
Drag the cursor to the desired icon, and release the mouse button.
The selected icon replaces the icon that was visible originally, and you can begin using the corresponding tool immediately.