Reference the template of the simple widget designer
To wire up the template with the designer, you must return its name via the LayoutTemplatePath property. It specifies the path to the embedded resource following the naming convention <Namespace>.<ResourceFolderPath>.<TemplateName>, where you must replace path slashes inside the ResourceFolderPath with dots.
For example, if you have project called SimpleWidget and the path to the template file is Resources/Views/SimpleWidgetDesigner.ascx, the LayoutTemplatePath property must return the following:
SimpleWidget.Resources.Views.SimpleWidgetDesigner.ascx
EXAMPLE: For more information about referencing the template of the designer in the designer's class, using the LayoutTemplatePath
property, see For developers: Full code of the widget designer class.