Found the solution:
I needed to edit my converter
because ToggleButton
uses a nullable bool
.
[ValueConversion(typeof(bool?), typeof(bool))]
public class InverseNullableBool : IValueConverter
{
public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
{
if (targetType != typeof(bool?))
throw new InvalidOperationException("The target must be a nullable boolean");
bool? b = (bool?)value;
return !(b.HasValue && b.Value);
}
}