Hi Amit,
It is in fact already supported to have cascade menu.
Please use the following settings:
<Item Text="Tasks" PictureName="TasksSmall!" Checked="false" Enabled="true" Tag="Task" Type="0" Visible="true" Clicked="ue_MenuTasksClicked" Selected="ue_MenuTasksSelected" >
<Item Text="Sub Task" PictureName="TasksSmall!" Checked="false" Enabled="true" Shortcut="Ctrl+Shift+Alt+B" Tag="Sub Task" Type="0" Visible="true" Clicked="ue_SubTaskClicked" Selected="ue_SubTaskSelected" />
<Item Text="Sub Task2" PictureName="TasksSmall!" Checked="false" Enabled="true" Tag="Sub Task 2" Type="0" Visible="true" Clicked="ue_SubTask2Clicked" Selected="ue_SubTask2Selected" />
</Item>
Then the RibbonBar will display as:
Best regards, Julie