How to add a TreeView inside a DropDownList

Step-1: Add a TextBox to your Page.

<asp:TextBox ID="Module" runat="server"></asp:TextBox>

Step-2: Add a Panel and place a treeview inside it.

<asp:Panel ID="pnl" runat="server">

<asp:TreeView ID="ModuleTreeView" runat="server" ShowLines="true" PopulateNodesFromClient="false" BackColor="#99CCFF" style="width:100%" ShowExpandCollapse="false">

</asp:TreeView>

</asp:Panel>

Step-3: Add a Ajax DropdownExtender and set its TargetControlID to the TextBox.

<asp:DropDownExtender ID="DropDownExtender1" runat="server" TargetControlID="Module"

DropDownControlID="pnl">

</asp:DropDownExtender>

Step-4: Then write your own method to bind the treeview.

(I have described about binding a treeview in My Previous Post  )

The final output is:

Thanks Shibashish Mohanty