You can add custom buttons and dropdowns to the toolbar in two ways:

1. Update the editor XML file (manual)

 a) Copy UltimateEditor.xml file from UltimateEditorInclude to your web page directory
 b) Rename UltimateEditor.xml as YourEditor.xml
 c) Set the EditorSource property of UltimateEditor to YourEditor.xml

    To add a button:
    1. Add the following line to YourEditor.xml:
        <ToolbarItem Type="Button" ID="SendMail" Command="None" ButtonFile="SendMail.gif"
      PostBackValue="SendMail" />
    2. Add the following line to UltimateEditorInclude/Languages/English.xml:
        <ToolbarItem ID="SendMail" ButtonTitle="Send Mail" />
    3. Create a new SendMail.gif button image, and copy it into the three Images folders under UltimateEditorInclude/Themes/*
    4. Add postback event handler for the button in PostBack event handler of UltimateEditor in your page code-behind

    To add a dropdown:
    1. Add the following line to YourEditor.xml:
        <ToolbarItem Type="DropDown" ID="InsertHTML" Command="None" />
    2. Add dropdown items and set client-side OnBeforeChange and OnAfterChange event handlers for the dropdown in
        ToolbarItemRender event handler of UltimateEditor in your page code-behind

2. Use the Toolbars collection (programming)

 a) Load the toolbars from the XML file specified by the EditorSource property to make modifications on it, or
 b) Add new buttons and dropdowns and set their properties as shown in part 1 above

 Please refer to the Server-Side API samples to learn more about programming the Toolbars collection.