最近的一个项目用基类的Template来包装窗体，新建的窗体里的一个按钮需要调用程序里的另外一个窗体，显示时需要把这个窗体加到mainWindow里的DocumentContainer（syncfusion的类库）里去，但在template里却不能直接得到主窗口的DocumentContainer，试了很多方法例如template里传值但太过复杂，google了一下，终于在stack overflow网站里找到了答案，他是用visual tree查找child控件，而我是查找parent控件，思路都是一样。方程是用generic写的，也就是你可以得到任意类型的控件。
程序如下：
''' <summary>
''' Finds a Child of a given item in the visual tree.
''' </summary>
''' <typeparam name="T">The type of the queried item.</typeparam>
''' <param name="root">A direct root of the queried item.</param>
''' <param name="parentName">name of parent control want to search</param>
''' <returns>The first parent item that matches the submitted type parameter.
''' If not matching item can be found, a null parent is being returned.</returns>
''' <remarks></remarks>
''' <writtenby name="" date="2011/02/05"></writtenby>
Private Shared Function FindParent(Of T As DependencyObject)(ByVal root As DependencyObject, ByVal parentName As String) As DependencyObject
Dim foundParent As T = Nothing
If root Is Nothing Then
Return foundParent
Else
Dim parent = VisualTreeHelper.GetParent(root)
Dim frameworkElement As FrameworkElement = parent
If frameworkElement IsNot Nothing AndAlso frameworkElement.Name = parentName Then
foundParent = parent
Else
'recursively drill up the tree
foundParent = FindParent(Of T)(parent, parentName)
End If
End If
Return foundParent
End Function
调用方法：
Dim objDependency As DependencyObject = CType(Me, DependencyObject)
Dim objDocumentContainer = FindParent(Of DependencyObject)(objDependency, "objDocumentContainer")
另外附图是visual tree的示意图，功能很强大，用的好的话帮助很大。
