static SpaceButton()
{
FrameworkPropertyMetadata metadata = new FrameworkPropertyMetadata();
metadata.DefaultValue = 1;
metadata.AffectsMeasure = true;
metadata.Inherits = true;
metadata.PropertyChangedCallback += OnSpacePropertyChanged;
SpaceProperty = DependencyProperty.Register("Space", typeof(int), typeof(SpaceButton), metadata, ValidateSpaceValue);
}