Gets or sets what button in the user interface (UI) is treated as the default button that receives the focus when form that contains the button is rendered. This property is not intended to be called from page developer code.
Assembly: System.Web (in System.Web.dll)
The code for this property overrides the base property inherited from the Panel class to hide the property from designers and prevent it from being affected by themes. Though it is public, this property is used internally by the Web Parts control set for default rendering of this control and is not intended to be used by page developers.
Available since 2.0