Populate dropDown in a custom ribbon on clicking a button

Hi All,

I created a custom Tab in Excel 2010 Ribbon having a button and a dropDown. The XML I used looks like -

PHP Code: 

<customUI xmlns="http://schemas.microsoft.com/office/2006/01/customui"> 
  <ribbon> 
    <tabs> 
      <tab id="MyTab" label="MyTab" insertBeforeMso="TabHome"> 
        <group id="Group1" label="My Group"> 
          <button id="Button1" label="Click Me" size="large" onAction="Macro1" /> 
          <dropDown id="dropDown1" label="Drop Down" /> 
        </group> 
      </tab> 
    </tabs> 
  </ribbon> 
</customUI> 


What I want to achieve is to write some code in Macro1 that will populate values One, Two, Three in the dropDown when Button1 is clicked. That means when the xlsm file is opened dropDown would be empty. It will be populated with values only when button is clicked.
Can any of you write a code snippet to get this done? Does this also need changes to be made to the XML (like adding callback actions)?

I used "Custom UI Editor for Microsoft Office" to add the xml to xlsm file.

Thanks in advance. Eagerly waiting for the answer.
- John

Thanks Pike!

Though I had already created the custom tab and controls in it, I'm checking out Andy Pope's RibbonX Visual Designer. It looks promising from first looks.

I'm also a big fan of Ron de Bruin. I'm referring some of his examples as well to figure our how I can accomplish what I have posted.