Click the Submit button below the editor or the Save toolbar button to validate the editor content.

You can validate the UltimateEditor control on the server-side after the page is submitted to ensure that
the user enters content in it.

All you need is to add a RequiredFieldValidator control, which comes with .NET Framework, to your page
and set its ControlToValidate property to the ID of your UltimateEditor control as follows:

<asp:RequiredFieldValidator id="RequiredFieldValidator1" runat="server"
ErrorMessage="* Please fill in the editor content."
ControlToValidate="UltimateEditor1" />

You can also call the Validate method of your RequiredFieldValidator control in PostBack event handler
of your UltimateEditor control for the toolbar items having their PostBackValue property set such as the
Save button in order to validate the editor content on the server-side.