//Create the RibbonTabItem
 RibbonTabItem homeItem = new RibbonTabItem();

//Create the RibbonGroup
RibbonGroup messagesGroup = new RibbonGroup();

    messagesGroup.Caption = "Messages";           
    messagesGroup.FlowDirection = System.Windows.FlowDirection.LeftToRight;
  
  //Set the Maximum size to ImageAndTextLarge
    RibbonGroup.SetMaximumSize(messagesGroup, RibbonToolSizingMode.ImageAndTextLarge);

 // Create a new button         
    ButtonTool btnNew = new ButtonTool();
            btnNew.LargeImage = ConvertPathToImageUri(@"\Images\New_Message_Large.png");
            btnNew.Content = "test";
            //add the button to the ribbongroup
            messagesGroup.Items.Add(btnNew);
            homeItem.RibbonGroups.Add(messagesGroup);

The btnNew is shown on the ribbon , as suspected in the tabitem , in the Ribbongroup.

My problem is that this button is showing its text and image mimimized.
and i set the property to this ?

//Set the Maximum size to ImageAndTextLarge
    RibbonGroup.SetMaximumSize(messagesGroup, RibbonToolSizingMode.ImageAndTextLarge);

any ideas would be appreciated.

Thx