没有按要求在点击文字控件后添加对用边框，且是通过拖动边框来改变边框大小和边框内控件大小

非常抱歉，并未完全理解您的需求。如果您需要在点击文字控件后添加对应边框，并通过拖动边框来改变边框大小和边框内控件大小，可以参考以下代码实现：

首先，在XAML中添加一个Canvas和一个按钮：

<Grid>
    <Canvas x:Name="canvas" Background="White" MouseDown="Canvas_MouseDown" MouseMove="Canvas_MouseMove" MouseUp="Canvas_MouseUp"/>
    <Button x:Name="addButton" Content="Add TextBlock" Click="addButton_Click"/>
</Grid>

在按钮的Click事件处理程序中，创建一个边框控件和一个TextBlock控件，并将其添加到Canvas中：

private void addButton_Click(object sender, RoutedEventArgs e)
{
    TextBlock textBlock = new TextBlock();
    textBlock.Text = "Click me!";
    textBlock.FontSize = 16;
    textBlock.Background = Brushes.LightGray;
    textBlock.Padding = new Thickness(10);
    textBlock.Cursor = Cursors.Hand;

    Border border = new Border();
    border.BorderThickness = new Thickness(1);
    border.BorderBrush = Brushes.Black;
    border.Child = textBlock;

    // 设置边框的大小和位置，并添加到Canvas中
    border.Width = 120;
    border.Height = 60;
    Canvas.SetLeft(border, 100);
    Canvas.SetTop(border, 100);
    canvas.Children.Add(border);

    // 添加鼠标事件
    border.PreviewMouseDown += new MouseButtonEventHandler(Border_PreviewMouseDown);
    border.PreviewMouseMove += new MouseEventHandler(Border_PreviewMouseMove);
    border.PreviewMouseUp += new MouseButtonEventHandler(Border_PreviewMouseUp);
}

在边框控件的PreviewMouseDown事件处理程序中，记录鼠标位置和边框位置，并将isDragging设置为true：

double lastX, lastY;
double lastWidth, lastHeight;
double lastLeft, lastTop;
bool isDragging = false;
Border selectedBorder;

private void Border_PreviewMouseDown(object sender, MouseButtonEventArgs e)
{
    // 记录鼠标位置和边框位置
    lastX = e.GetPosition(canvas).X;
    lastY = e.GetPosition(canvas).Y;
    selectedBorder = (Border)sender;
    lastWidth = selectedBorder.Width;
    lastHeight = selectedBorder.Height;
    lastLeft = Canvas.GetLeft(selectedBorder);
    lastTop = Canvas.GetTop(selectedBorder);
    isDragging = true;

    // 将边框置于最前面
    selectedBorder.SetValue(Canvas.ZIndexProperty, canvas.Children.Count);
}

在边框控件的PreviewMouseMove事件处理程序中，计算鼠标移动的距离，并根据移动的距离改变边框的大小和位置：

private void Border_PreviewMouseMove(object sender, MouseEventArgs e)
{
    if (isDragging)
    {
        // 计算鼠标移动的距离
        double deltaX = e.GetPosition(canvas).X - lastX;
        double deltaY = e.GetPosition(canvas).Y - lastY;

        // 改变边框的大小和位置
        double newWidth = lastWidth + deltaX;
        double newHeight = lastHeight + deltaY;
        if (newWidth > 0 && newHeight > 0)
        {
            selectedBorder.Width = newWidth;
            selectedBorder.Height = newHeight;
            Canvas.SetLeft(selectedBorder, lastLeft + deltaX);
            Canvas.SetTop(selectedBorder, lastTop + deltaY);
        }
    }
}

在边框控件的PreviewMouseUp事件处理程序中，释放鼠标，完成边框移动改变大小的操作：

private void Border_PreviewMouseUp(object sender, MouseButtonEventArgs e)
{
    isDragging = false;
}

这样，当用户点击按钮时，会在Canvas上添加一个包含TextBlock的边框。当用户点击边框时，会出现边框，并可以通过拖动边框来改变边框大小和边框内控件大小。