How to make such a message? I can not find anywhere

  • four
    WinForms or WPF? Correct the question, add the desired tag. - Bulson
  • Now you need to clarify the following: you do not know how to use ErrorProvider or you are not satisfied visually, how does it display an error message? - Bulson
  • @Bulson does not like visually - FusRoDah

1 answer 1

You might like the easy Tooltip on a TextChanged event:

 private void textBox1_TextChanged(object sender, EventArgs e) { TextBox TB = (TextBox)sender; int VisibleTime = 500; ToolTip tt = new ToolTip(); if (/*если текст введен не верно*/) { tt.Show("Ошибка ввода", TB, 10, 20, VisibleTime); } }