If a menu item in the RadMenu control contains any children, they are shown depending on a user action. There are two opening modes that recognize the following two actions:
The child items are shown when the mouse is over the parent.
The child items are shown when the user clicks on the parent.
This behavior of the RadMenu control can be controlled via the ClickToOpen property. The default value is False which means that the child items are displayed upon a hover action.
Setting the property to True will make the child items appear upon a mouse click on their parent. Note that the children do not automatically hide, but they will wait for a mouse click again.
<telerik:RadMenu ClickToOpen="True"> ... </telerik:RadMenu>
To illustrate this case here is a snapshot of the menu upon a hover:
and upon a mouse click: