The default behavior of property BackColor of a TextBox is as follows: when enabled, it is White (SystemColors.Window), w
BackColor
TextBox
White
SystemColors.Window
SystemColors.Window is (usually) white. Use SystemColors.Control.
SystemColors.Control
You could, of course, cache the color in use when you set it to your own, then use that to reset it. In the end, though, either approach will work.