WPF Change Style’s Brush Color

I don't think that you can keep this Brush in your resource dictionary and use binding to pull in the color. Since the brush is only created once (which is why you want it in the resource dictionary in the first place), at the time of creation WPF doesn't know where it will be used, so it can't pull in the value for the color.

If the color were kept in Setings, for example, that would probably work - but I'm guessing that won't help you, because you probably want the color to change on each control that it is used on (otherwise, you could just hard code the color or it would already be in settings).

Maybe you could create a RadialGradientBrush subclass, and expose the first GradientStop color as a DependencyProperty? You could then create an instance of this subclass wherever you need it, and use binding to pull in the correct color there.

You can use a ValueConverter that inverts a bool property for you.

XAML:

IsEnabled="{Binding Path=IsReadOnly, Converter={StaticResource InverseBooleanConverter}}"

Converter:

[ValueConversion(typeof(bool), typeof(bool))]
    public class InverseBooleanConverter: IValueConverter
    {
        #region IValueConverter Members

        public object Convert(object value, Type targetType, object parameter,
            System.Globalization.CultureInfo culture)
        {
            if (targetType != typeof(bool))
                throw new InvalidOperationException("The target must be a boolean");

            return !(bool)value;
        }

        public object ConvertBack(object value, Type targetType, object parameter,
            System.Globalization.CultureInfo culture)
        {
            throw new NotSupportedException();
        }

        #endregion
    }