Thank you for writing back.
I would like to clarify that the attached sample in my previous answer demonstrates only the idea of how you can accomplish this task.
In short, you need to do the following:
- Create a RadDropDownListElement, set MinimumSize to 140,20 and put it in a RadRibbonBar group.
- Add items in the RadDropDownListElement for each theme that you want to be available in the drop down.
- Handle SelectedIndexChanged event and set ThemeResolutionService.ApplicationThemeName to the Text of the selected Item.
As to the exception, most likely this error appears because Visual Studio is not able to load the Telerik.WinControls.dll assembly that defines the public class TelerikToolboxCategoryAttribute.
Please make sure that you have the correct version of the assembly referenced. If this does not help, you can try uninstalling our suite, clearing your GAC from the remaining Telerik assemblies if such exist, install the suite again and update your project references.
In regards to the C# code, you can easily convert the code from this topic by using the online code convertor tool
Please refer to the attached VB project.
I hope this helps.
the Telerik team