ASP.NET 3.5 and above only

Obout.Ajax.UI Controls - HTML Editor - Full custom buttons set

Here you can see how to set all available buttons for the top toolbar (like TopToolbar.Appearance="Full") in Editor control with TopToolbar.Appearance="Custom".
If you don't want to use the full buttons set, just copy the text below and remove buttons you don't want to see.
<%@ Register Assembly="Obout.Ajax.UI" Namespace="Obout.Ajax.UI.HTMLEditor" TagPrefix="obout" %>
<%@ Register Assembly="Obout.Ajax.UI" Namespace="Obout.Ajax.UI.HTMLEditor.ToolbarButton" TagPrefix="obout" %>
<obout:Editor runat="server" Id="editor" Height="500px" Width="100%">
      <TopToolbar Appearance="Custom">
            <AddButtons>
                  <obout:ButtonsGroup runat="server"><Buttons>
                        <obout:Undo runat="server" />
                        <obout:Redo runat="server" />
                        <obout:HorizontalSeparator runat="server" />
                  </Buttons></obout:ButtonsGroup>
                  <obout:ButtonsGroup runat="server"><Buttons>
                        <obout:Bold runat="server" />
                        <obout:Italic runat="server" />
                        <obout:Underline runat="server" />
                        <obout:StrikeThrough runat="server" />
                        <obout:SubScript runat="server" />
                        <obout:SuperScript runat="server" />
                        <obout:ToLowerCase runat="server" />
                        <obout:ToUpperCase runat="server" />
                        <obout:HorizontalSeparator runat="server" />
                  </Buttons></obout:ButtonsGroup>
                  <obout:ForeColorGroup runat="server" />
                  <obout:HorizontalSeparator runat="server" />
                  <obout:BackColorGroup runat="server" />
                  <obout:HorizontalSeparator runat="server" />
                  <obout:ButtonsGroup runat="server"><Buttons>
                        <obout:GetFormat runat="server" />
                        <obout:ApplyFormat runat="server" />
                        <obout:RemoveStyles runat="server" />
                        <obout:HorizontalSeparator runat="server" />
                  </Buttons></obout:ButtonsGroup>
                  <obout:FontName runat="server" />
                  <obout:HorizontalSeparator runat="server" />
                  <obout:FontSize runat="server" />
                  <obout:HorizontalSeparator runat="server" />
                  <obout:Header runat="server" />
                  <obout:HorizontalSeparator runat="server" />
                  <obout:ButtonsGroup runat="server"><Buttons>
                        <obout:Cut runat="server" />
                        <obout:Copy runat="server" />
                        <obout:Paste runat="server" />
                        <obout:PasteText runat="server" />
                        <obout:PasteWord runat="server" />
                        <obout:HorizontalSeparator runat="server" />
                  </Buttons></obout:ButtonsGroup>
                  <obout:ButtonsGroup runat="server"><Buttons>
                        <obout:DecreaseIndent runat="server" />
                        <obout:IncreaseIndent runat="server" />
                        <obout:HorizontalSeparator runat="server" />
                  </Buttons></obout:ButtonsGroup>
                  <obout:ButtonsGroup runat="server"><Buttons>
                        <obout:MakeNotEditable runat="server" />
                        <obout:HorizontalSeparator runat="server" />
                  </Buttons></obout:ButtonsGroup>
                  <obout:ButtonsGroup runat="server"><Buttons>
                        <obout:Paragraph runat="server" />
                        <obout:JustifyLeft runat="server" />
                        <obout:JustifyCenter runat="server" />
                        <obout:JustifyRight runat="server" />
                        <obout:JustifyFull runat="server" />
                        <obout:RemoveAlignment runat="server" />
                        <obout:HorizontalSeparator runat="server" />
                  </Buttons></obout:ButtonsGroup>
                  <obout:ButtonsGroup runat="server"><Buttons>
                        <obout:Ltr runat="server" />
                        <obout:Rtl runat="server" />
                        <obout:RemoveDirection runat="server" />
                        <obout:HorizontalSeparator runat="server" />
                  </Buttons></obout:ButtonsGroup>
                  <obout:ButtonsGroup runat="server"><Buttons>
                        <obout:OrderedList runat="server" />
                        <obout:BulletedList runat="server" />
                        <obout:HorizontalSeparator runat="server" />
                  </Buttons></obout:ButtonsGroup>
                  <obout:ButtonsGroup runat="server"><Buttons>
                        <obout:InsertLink runat="server" />
                        <obout:RemoveLink runat="server" />
                        <obout:InsertHR runat="server" />
                        <obout:InsertIcon runat="server" />
                        <obout:InsertSpecialCharacter runat="server" />
                        <obout:ImportDocument runat="server" />
                        <obout:HorizontalSeparator runat="server" />
                  </Buttons></obout:ButtonsGroup>
                  <obout:ButtonsGroup runat="server"><Buttons>
                        <obout:InsertTable runat="server" />
                        <obout:InsertDiv runat="server" />
                        <obout:InsertImage runat="server" />
                        <obout:InsertFlash runat="server" />
                        <obout:InsertMedia runat="server" />
                        <obout:InsertFlashVideo runat="server" />
                        <obout:HorizontalSeparator runat="server" />
                  </Buttons></obout:ButtonsGroup>
                  <obout:ButtonsGroup runat="server"><Buttons>
                        <obout:InsertForm runat="server" />
                        <obout:InsertCheckBox runat="server" />
                        <obout:InsertRadio runat="server" />
                        <obout:InsertTextBox runat="server" />
                        <obout:InsertPassword runat="server" />
                        <obout:InsertHidden runat="server" />
                        <obout:InsertButton runat="server" />
                        <obout:InsertSubmit runat="server" />
                        <obout:InsertReset runat="server" />
                        <obout:HorizontalSeparator runat="server" />
                  </Buttons></obout:ButtonsGroup>
                  <obout:ButtonsGroup runat="server"><Buttons>
                        <obout:InsertAnchor runat="server" />
                        <obout:AnchorsToggle runat="server" />
                        <obout:HorizontalSeparator runat="server" />
                  </Buttons></obout:ButtonsGroup>
                  <obout:ButtonsGroup runat="server"><Buttons>
                        <obout:SpellCheck runat="server" />
                        <obout:SelectAll runat="server" />
                        <obout:SelectNone runat="server" />
                        <obout:Print runat="server" />
                        <obout:ContextMenuButton runat="server" />
                  </Buttons></obout:ButtonsGroup>
                  <obout:TextIndicator runat="server" />
            </AddButtons>
      </TopToolbar>
</obout:Editor>