DropDown is an ASP.NET AJAX extender that can be attached to almost any ASP.NET control to provide a SharePoint-style drop-down menu. The displayed menu is merely another panel or control. In the above sample the drop-down is a Panel which contains LinkButtons. The drop-down is activated by left- or right-clicking the attached control. If the behavior is attached to a Hyperlink or LinkButton, clicking on the link itself will operate normally.

The control above is initialized with this code. The italic properties are optional:

<ajaxToolkit:DropDownExtender runat="server" ID="DDE"
    TargetControlID="TextLabel" 
    DropDownControlID="DropPanel" />

• TargetControlID - The ID of the control which needs a drop-down.
• DropDownControlID - The ID of the control which will be displayed as the dropdown.
• Animations - Generic animations for the DropDown extender. See the Using Animations walkthrough and Animation Reference for more details.
  • OnShow - The OnShow animation will be played each time the dropdown is displayed. The dropdown will be positioned correctly but hidden. The animation can use <HideAction Visible="true" /> to display the dropdown along with any other visual effects.
  • OnHide - The OnHide animation will be played each time the dropdown is hidden.