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This entry has been published on 2019-04-11 and may be out of date.

Last Updated on 2019-04-11.

[:en]Useful snippet for adding a placeholder text feature to a common Windows Forms TextBox like you might know it from HTML’s <input> tag.

Add e.g. to your ExtensionMethods:

private const int EM_SETCUEBANNER = 0x1501;
[DllImport("user32.dll", CharSet = CharSet.Auto)]
private static extern Int32 SendMessage(IntPtr hWnd, int msg, int wParam, [MarshalAs(UnmanagedType.LPWStr)]string lParam);

public static void SetPlaceholder(this TextBox box, string text)
    SendMessage(box.Handle, EM_SETCUEBANNER, 0, text);