The DHTML Menu Extension adds several new elements to the Macromedia Dreamweaver's interface.
Insertbar icon
Located in the "Common" section of the Insertbar, the DHTML Menu icon works like any other icon in Macromedia Dreamweaver. You may press it or drag into some location of your webpage to start editing a new menu.

Insert menu entry
Works exactly the same way as the Insertbar icon.

Floating window
Allows you to inspect, add, remove and move the menus contained in the current webpage. It can be displayed (or hidden) by selecting Window > DHTML Menu Extension menu entry. You can dock this window to a side panel by grabbing it by its title bar and dragging there. A bold black line will indicate the docking position during the drag.
