自定义文本框控件

You would just need to handle three TextBox events, in the Designer set the text of the TextBox to "username" and make it Font Italics then set TextBox BackColor to LightYellow,the rest is handled by Event handlers...

     private void textBox1_TextChanged(object sender, EventArgs e)
    {
        if (textBox1.Text == "")
            ChangeTextBoxtoWatermark();
    }

    private void textBox1_MouseEnter(object sender, EventArgs e)
    {
        if (textBox1.Text == "username")
        {
            textBox1.Text = "";
            textBox1.Font = new Font(this.Font, FontStyle.Regular);
            textBox1.BackColor = Color.White;
        }
    }

    private void textBox1_MouseLeave(object sender, EventArgs e)
    {
        if (textBox1.Text == "")
            ChangeTextBoxtoWatermark();
    }

    private void ChangeTextBoxtoWatermark()
    {
        textBox1.Font = new Font(this.Font, FontStyle.Italic);
        textBox1.BackColor = Color.LightYellow;
        textBox1.Text = "username";
    }

的 我已经检查它，它工作得很好:) 的

I have checked it and it works fine :)

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