Question

First I will give you my code and after that I will ask my question.

namespace LinearGradientBrushBinding
{
    public partial class LinearGradBrush : UserControl
    {
        public LinearGradBrush()
        {
            InitializeComponent();
        }

        class LinearGradBrushProp : DependencyObject
        {
            public static DependencyProperty _background;

            static void BackgroundBrush()
            {
                _background = DependencyProperty.Register(
                    "_background", typeof(Brush), typeof(LinearGradBrushProp));
            }

            [Description("CuloareBG"), Category("Z")]
            public Brush Background
            {
                get { return (Brush)GetValue(_background); }
                set { SetValue(_background, value); }
            }
        }
    }
}

As you can see I have an UserControl which has in it a class. My question is why I don’t see in the Property window (right side of UserControl.Xaml) of my control the category Z with a brush in it.

Answer 1

why I don’t see in the Property window (right side of UserControl.Xaml) of my control the category Z with a brush in it.

Quite simply because your LinearGradBrush doesn’t contain a property annotated with the category Z.

Your LinearGradBrush contains a (private) inner class that does have such a property, but there’s no way the property editor can know which instance of this inner class to assign a property value to. (The property editor might not even be able to see this inner class, given that it is private.)

I recommend that you move this property out of your inner class and get rid of the class. I cannot honestly see a reason why you would need to use an inner class here.

Also, I’d like to point out that your dependency property isn’t declared correctly. It doesn’t use the correct naming conventions, and I cannot see any call to the BackgroundBrush() method which initialises the dependency property. I would expect the property to be declared as follows (note the name of the field, the fact that it is readonly and that the first parameter of the Register method is the name of the property):

public static readonly DependencyProperty BackgroundProperty =
    DependencyProperty.Register("Background", typeof(Brush), typeof(LinearGradBrush));

[Description("CuloareBG"), Category("Z")]
public Brush Background
{
    get { return (Brush)GetValue(BackgroundProperty); }
    set { SetValue(BackgroundProperty, value); }
}

I made this change to your code, switched to another XAML page (i.e. not LinearGradBrush.xaml), and added your control to this XAML page as an element <local:LinearGradBrush />. While the text cursor was over this element, the Background property appeared in the Z category of the properties window.