public SwkbdAppletDialog(string mainText, string secondaryText, string placeholder)
{
MainText = mainText;
SecondaryText = secondaryText;
DataContext = this;
_placeholder = placeholder;
InitializeComponent();
Input.Watermark = _placeholder;
Input.AddHandler(TextInputEvent, Message_TextInput, RoutingStrategies.Tunnel, true);
SetInputLengthValidation(0, int.MaxValue); // Disable by default.
}