You can initialize toolbar items either programmatically, or manually by updating the editor source XML file.

You can set the Selected property of buttons such as Bold to a boolean like "True", SelectedValue property of
special buttons such as ForeColor to a color like "Blue", or SelectedValue property of dropdown items such as
FontSize to a value like "4".

In this sample, Bold, FontSize and ForeColor are selected programmatically in the code behind file, while
Italic, FontName and BackColor are selected statically in the InitializeToolbarItems.xml file.