dropDown

This control allows the user to select from a list of possible choices.

The value returned is the list index.
In the object model this is RibbonDropDown
A dropdown control can contain items or even buttons after its selection items.
This control is similar to a gallery control but the gallery control also allows items to be arranged in a grid.
You cannot manipulate the buttons collections at runtime but you can show and hide existing buttons to create the equivalent of a dynamic list.
RibbonDropDown has an Items collection that contains RibbonDropDownItem controls.
This collection can be modified at runtime.

link - learn.microsoft.com/en-us/openspecs/office_standards/ms-customui/700e4451-8706-40c5-8d7b-896e4ae21b69 

<customUI xmlns="http://schemas.microsoft.com/office/2009/07/customui"> 
    <ribbon startFromScratch="false"> 
        <tabs> 
            <tab id="CustomTab" label="My Tab"> 
                <group id="Group1" label="MyGroup"> 
                    <dropDown id="MyDropDown" 
                              sizeString="AAAAAAAAAAAAAAAAAAAAAAA" 
                              onAction="DropDown_OnAction" 
                              getEnabled="DropDown_OnGetEnabled" 
                              getLabel="DropDown_OnGetLabel" 
                              getSelectedItemIndex="DropDown_OnGetSelectedItemIndex" 
                              getShowLabel="DropDown_OnGetShowLabel" 
                              getVisible="DropDown_OnGetVisible"> 
                        <item id="One" label="Mon"/> 
                        <item id="Two" label="Tue"/> 
                        <item id="Three" label="Wed"/> 
                        <button id="button" label="Another Button" onAction="Button_OnAction" /> 
                    </dropDown> 
                </group> 
            </tab> 
        </tabs> 
    </ribbon> 
</customUI> 

Attributes (properties)

Children

This control can contain the following controls

C# Events (design-time)

These events can be accessed if you use the Visual Studio Ribbon Designer.

' C#
void DropDown_ButtonClick(object sender, 
                          RibbonControlEventArgs e) 
{ 
} 

void DropDown_ItemsLoading 
{ 
} 

void DropDown_SelectionChanged( 
{ 
} 

Callbacks (run-time)

' VBA
Public Sub DropDown_OnAction( _ 
   ByRef control As Office.IRibbonControl, _ 
   ByRef dropdownID As String, _ 
   ByRef selectedIndex As Variant) 

   Call MsgBox("OnAction" & selectedIndex) 
End Sub 

' C# Equivalent
void DropDown_OnAction( 
   Office.IRibbonControl control, 
   string dropdownID, 
   int selectedIndex) 
{ 
} 

' VBA
Public Sub DropDown_OnGetEnabled( _ 
   ByRef control As Office.IRibbonControl, _ 
   ByRef Enabled As Variant) 

   Enabled = True 
End Sub 

' C# Equivalent
bool DropDown_OnGetEnabled( 
   Office.IRibbonControl control) 
{ 
} 

' VBA
Public Sub DropDown_OnGetImage( _ 
   ByRef control As Office.IRibbonControl, _ 
   ByRef Image As Variant) 

End Sub 

' C# Equivalent
System.Drawing.Bitmap DropDown_OnGetImage( 
   Office.IRibbonControl control) 
{ 
   return new System.Drawing.Bitmap(Properties.Resources.untitled); 
} 

' VBA
Public Sub DropDown_OnGetItemCount( _ 
   ByRef control As Office.IRibbonControl, _ 
   ByRef Count As Variant) 

   Count = 5 
End Sub 

' C# Equivalent
int DropDown_OnGetItemCount( 
   Office.IRibbonControl control) 
{ 
} 

' VBA
' Generate Callbacks does not generate this
Public Sub DropDown_OnGetItemID( _ 
   ByRef control As Office.IRibbonControl, _ 
   ByRef Index As Integer, _ 
   ByRef ItemID As Variant) 
   
   ItemID = "ID" & Index 
End Sub 

' C# Equivalent
string DropDown_OnGetItemID( 
   Office.IRibbonControl control, 
   int Index) 
{ 
} 

' VBA
Public Sub DropDown_OnGetItemImage( _ 
   ByRef control As Office.IRibbonControl, _ 
   ByRef Index As Integer, _ 
   ByRef Image As Variant) 

   Set Image = LoadPicture(ThisWorkbook.Path & "image_" & index + 1 & ".jpg") 
   Set Image = Application.Commandbars.GetImageMso("",16,16) 
End Sub 

' C# Equivalent
string DropDown_OnGetItemImage( 
   Office.IRibbonControl control, 
   int Index) 
{ 
} 

' VBA
Public Sub DropDown_OnGetItemLabel( _ 
   ByRef control As Office.IRibbonControl, _ 
   ByRef Index As Integer, _ 
   ByRef ItemLabel As Variant) 

   ItemLabel = "Item - " & Index 
End Sub 

' C# Equivalent
string DropDown_OnGetItemLabel( 
   Office.IRibbonControl control, 
   int Index) 
{ 
} 

' Generate Callbacks does not generate this
Public Sub DropDown_OnGetItemScreentip( _ 

' Generate Callbacks does not generate this
Public Sub DropDown_OnGetItemSupertip( _ 

' VBA
Public Sub DropDown_OnGetKeytip( _ 
   ByRef control As Office.IRibbonControl, _ 
   ByRef Keytip As Variant) 

End Sub 

' C# Equivalent
string DropDown_OnGetKeytip( 
   Office.IRibbonControl control) 
{ 
} 

' VBA
Public Sub DropDown_OnGetLabel( _ 
   ByRef control As Office.IRibbonControl, _ 
   ByRef Label As Variant) 

   Label = "My Label Text" 
End Sub 

' C# Equivalent
string DropDown_OnGetLabel( 
   Office.IRibbonControl control) 
{ 
} 

' VBA
Public Sub DropDown_OnGetScreentip( _ 
   ByRef control As Office.IRibbonControl, _ 
   ByRef Screentip As Variant) 

End Sub 

' C# Equivalent
string DropDown_OnGetScreentip( 
   Office.IRibbonControl control) 
{ 
} 

' VBA
Public Sub DropDown_OnGetSelectedItemID( _ 
   ByRef control As Office.IRibbonControl, _ 
   ByRef SelectedItem As Variant) 

End Sub 

' C# Equivalent
string DropDown_OnGetSelectedItemId( 
   Office.IRibbonControl control) 
{ 
} 

' VBA
' Generate Callbacks does not generate this
Public Sub DropDown_OnGetSelectedItemIndex( _ 
   ByRef control As IRibbonControl, _ 
   ByRef returnedVal As Variant) 
   
   returnedVal = 1 
End Sub 

' C# Equivalent
int DropDown_OnGetSelectedItemIndex( 
   Office.IRibbonControl control) 
{ 
} 

' VBA
Public Sub DropDown_OnGetShowImage( _ 
   ByRef control As Office.IRibbonControl, _ 
   ByRef ShowImage As Variant) 

End Sub 

' C# Equivalent
string DropDown_OnGetShowImage( 
   Office.IRibbonControl control) 
{ 
} 

' VBA
Public Sub DropDown_OnGetShowLabel( _ 
   ByRef control As Office.IRibbonControl, _ 
   ByRef ShowLabel As Variant) 

   ShowLabel = True 
End Sub 

' C# Equivalent
string DropDown_OnGetShowLabel( 
   Office.IRibbonControl control) 
{ 
} 

' VBA
Public Sub DropDown_OnGetSupertip( _ 
   ByRef control As Office.IRibbonControl, _ 
   ByRef Supertip As Variant) 

End Sub 

' C# Equivalent
string DropDown_OnGetSupertip( 
   Office.IRibbonControl control) 
{ 
} 

' VBA
Public Sub DropDown_OnGetVisible( _ 
   ByRef control As Office.IRibbonControl, _ 
   ByRef Visible As Variant) 

   Visible = True 
End Sub 

' C# Equivalent
string DropDown_OnGetVisible( 
   Office.IRibbonControl control) 
{ 
}