private string Notes = "提示文本"; private void textBox1_Leave(object sender, EventArgs e) { // 退出失去焦點,重新顯示 if (string.IsNullOrEmpty(textBox1.Text)) { textBox1.ForeColor = Color.DarkGray; this.textBox1.Text = Notes; } } private void textBox1_Enter(object sender, EventArgs e) { // 進入獲得焦點,清空 if (textBox1.Text == Notes) { textBox1.ForeColor = Color.Black; this.textBox1.Text = ""; } }