public NextStepCommand(QGradientViewModel wvm) : base(wvm)
 {
 }
 public SaveQCommand(QGradientViewModel wvm) : base(wvm)
 {
 }
 public QGradientViewCommand(QGradientViewModel gvm)
 {
     _gvm = gvm;
 }
 public PreviousStepCommand(QGradientViewModel wvm) : base(wvm)
 {
 }