Handle the
TextBox.TextChanged[
^] event. Once you have set the textbox content as required in your Form.Load or Form constructor, link in to handle the event for all three TextBoxes:
textBox1.TextChanged += new EventHandler(TextBox_TextChanged);
textBox2.TextChanged += new EventHandler(TextBox_TextChanged);
textBox3.TextChanged += new EventHandler(TextBox_TextChanged);
button1.Enabled = false;
Then, in the handler routine, enable the save button.
void TextBox_TextChanged(object sender, EventArgs e)
{
button1.Enabled = true;
}
You could get clever, and check the current value against the default in the handler, but that's up to you!