VSTO Addin disable builtin outlook button on Appointment (Recurring) - vsto

Question

I am developing an Outlook Addin (VSTO, C#). I created the Addin with the following steps in VS: New->Project , then
From all what I learned in the meantime I fear that this DOES NOT create a COM-AddIn. But all tutorials listed below refer to COM AddIns.
I am looking for a step by step tutorial of how I can disable the builtin OUtlook Button which converts an appointment into a recurring appointment.
I already read a lot about fluent ribbons, like here
Programmaticaly disable existing button in outlook compose window ribbon
https://learn.microsoft.com/de-de/office/vba/library-reference/concepts/overview-of-the-office-fluent-ribbon
But I am just no able to put this into action for my purpose:
1.) I implemented in my Addin Class
public partial class ThisAddIn : Office.IRibbonExtensibility
...
string Office.IRibbonExtensibility.GetCustomUI(string RibbonID)
{
throw new NotImplementedException();
}
I set the breakpoint on the Exception. But running the addin (in Debugger) never stopped at that point.
I tried what is mentioned here:
IRibbonExtensibility GetCustomUI not called
I added [ComVisible(true)] to the VSTO AddIn Class. Does not work either. I also made sure that the Addin is still loaded.
2.) I am not sure how I could that with Outlook. It says that Outlook has several xml files (one per inspector?)
3.) I am not sure whether I would be able to dynamically change the buttons. Athough the second tutorial talks about that, but i am not sure if callbacks are the right concept here, because my application activley wants to decide when a button should be active/inactive, so there is no waiting for a callback to happen?
I know that the links provided above contain step-by-step tutorials. But there are just too many open questions to these tutorials.

Answer 1

You have already found a complete guide on how to repurpose a ribbon button. Just use command tag with the getEnabled attribute defined in your ribbon XML markup. For example:
<?xml version="1.0" encoding="UTF-8"?>
<customUI xmlns="http://schemas.microsoft.com/office/2009/07/customui" onLoad="Ribbon_Load">
<commands>
<command idMso="Permissions" getEnabled="OnGetEnabled" />
</commands>
</customUI>
You can repurpose built-in ribbon controls, see Temporarily Repurpose Commands on the Office Fluent Ribbon for more information.
VSTO provides two ways of customizing the Fluent UI:
Walkthrough: Create a custom tab by using the Ribbon Designer
Walkthrough: Create a custom tab by using Ribbon XML
Unfortunately, the UI designer doesn't support all the features of the Fluent UI. So, you need to stick with a raw XML markup described in one of the articles mentioned above.