BinaryRibbonSplitButtonControl

Use it where one choice is by far the most common: "Insert date" with the date formats in the drop-down, "Save" with Save As, "Approve" with Approve with comments.

The main part

A click on the picture and caption raises MenuItem.Click and runs MenuItem.Command, as a plain button would – on the release of the mouse button, or on the press with ClickMode set to Press. It does not open the drop-down. A click also closes any ribbon pop-up the button is in.

The drop-down

The alternatives are the button's ItemsControl.Items – usually BinaryRibbonMenuItem controls – with BinaryRibbonDropDownButton.DropDownHeaderContent and BinaryRibbonDropDownButton.DropDownFooterContent above and below them, exactly as for BinaryRibbonDropDownButton. Enter or Space opens the drop-down from the keyboard, and setting BinaryRibbonDropDownButton.IsDropDownCurrentlyPressed opens it from code.

Size and keyboard

Large, the main part is the picture and the arrow part is the caption beneath it; medium and small, the arrow is a narrow strip at the right. A key tip (BinaryKeyTip.AccessKeyProperty) clicks the main part.

<ribbon:BinaryRibbonGroup TitleText="Insert"
        xmlns:ribbon="clr-namespace:Binarymission.WPF.Controls.Office;assembly=Binarymission.WPF.Controls.BinaryRibbon">
    <ribbon:BinaryRibbonSplitButtonControl Content="Insert date"
                                           LargeImage="Images/Calendar32.png"
                                           SmallImage="Images/Calendar16.png"
                                           ribbon:BinaryKeyTip.AccessKey="D"
                                           Click="OnInsertToday">
        <ribbon:BinaryRibbonMenuItem Header="09/10/2026"      Click="OnInsertShortDate" />
        <ribbon:BinaryRibbonMenuItem Header="9 October 2026"  Click="OnInsertLongDate" />
        <ribbon:BinaryRibbonMenuItem Header="Date and time"   Click="OnInsertDateTime" />
    </ribbon:BinaryRibbonSplitButtonControl>
</ribbon:BinaryRibbonGroup>

private void OnInsertToday(object sender, RoutedEventArgs e)
{
    // Click bubbles, so the entries' clicks reach this handler too: act only on the button's own.
    if (e.OriginalSource != sender) return;
    letterEditor.CaretPosition.InsertTextInRun(DateTime.Today.ToLongDateString());
}