How is it possible to use a var after "this."

i want to set the Background color of a TextBlock to Blue.

 Brush blue = new SolidColorBrush(Colors.LightBlue); //Working Fine


//Click on the TextBlock (Working Fine) 
    private void MouseDown_TextBlock(object sender, MouseButtonEventArgs e)
    {
    
        var stand = ((TextBlock)sender).Name; //Here i am getting the Name of the TextBlock (Working Fine)
        this.stand.Background = blue; //This is not working here
    }

>Solution :

If you want to access the control you receive as Sender in an event, just cast it to the appropriate class:

private void textBlock1_MouseDown(object sender, MouseButtonEventArgs e)
{
    // Get sender as TextBlock
    TextBlock standTextBlockFromSender = (TextBlock)sender;
    standTextBlockFromSender.Background = new SolidColorBrush(Color.FromArgb(255, 0, 0, 255));
}

If you want to find the control by name, you can use the FindName method.

private void textBlock1_MouseDown(object sender, MouseButtonEventArgs e)
{
    // Get name of sender 
    string stand = ((TextBlock)sender).Name;

    // Get TextBlock by name
    TextBlock standTextBlockFromName = (TextBlock)this.FindName(stand);

    standTextBlockFromName.Background = new SolidColorBrush(Color.FromArgb(255, 0, 0, 255));
}