Builds the current template's visual tree if necessary, and returns a value that indicates whether the visual tree was rebuilt by this call.
Assembly: PresentationFramework (in PresentationFramework.dll)
Applications can call this method to guarantee that the visual tree of an element is complete. This guarantee step might be necessary if code will be checking the child elements in the tree. For typical element logic within applications, calling is not necessary, because templates will be applied to elements at an appropriate point in their lifetimes automatically.
is called on every Measure pass by the WPF framework-level layout system.
FrameworkElement derived classes can use the OnApplyTemplate class handler to be notified of cases where this method was called explicitly, or by the layout system. OnApplyTemplate is called after the template is completely generated and attached to the logical tree.