Check out example codes for "textbox gotfocus wpf". It will help you in understanding the concepts better.
Code Example 1
<TextBox Name="tb"
GotFocus="tb_GotFocus" />
Code Example 2
private void tb_GotFocus(object sender, RoutedEventArgs e)
{
TextBox tb = sender as TextBox;
if (tb != null) {
tb.SelectAll(); //select all text in TextBox
}
}
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