How to add multiple buttons in a TabPanelItem
<syncfusion:Ribbon.TabPanelItem>
<syncfusion:RibbonButton SizeForm="Small" Label="Refresh"/>
<syncfusion:RibbonButton SizeForm="Small" Label="Help"/>
<syncfusion:RibbonButton SizeForm="Small" Label="Close"/>
</syncfusion:Ribbon.TabPanelItem>