Customization Guide (.pdf) - Documentation & Online Help - Autodesk

A visual indicator bar is displayed to indicate the location where the
command or control will be added when the pointing device button is
released.
8 Once the splitter bar is in the location where you want to insert the
command or control, release the pointing device button.
9 Adjust the properties of the drop-down as desired to control the
appearance of the drop-down and the commands under the drop-down.
on page 164
10 If the drop-down will use the Split behavior, add a command to the
Primary Command node under the drop-down to set the command for
the main button.
11 Click Apply.
Quick Reference
Commands
CUI
Manages the customized user interface elements in the product.
Ribbon You can customize the ribbon by creating and modifying ribbon panels and
organizing ribbon panels into groups of task-based tools with ribbon tabs.
148 | Chapter 4 User Interface Customization