[MarkupExtensionReturnType(typeof(string))]
public class StringFormatExtension : MarkupExtension
{
    ResourceReferenceExpressionConverter rrconverter = new ResourceReferenceExpressionConverter();
    List<object> values = new List<object>();

    public StringFormatExtension(object format) { values.Add(format); }
    public StringFormatExtension(object format, object arg0) : this(format) { values.Add(arg0); }
    public StringFormatExtension(object format, object arg0, object arg1) : this(format, arg0) { values.Add(arg1); }
    public StringFormatExtension(object format, object arg0, object arg1, object arg2) : this(format, arg0, arg1) { values.Add(arg2); }
    public StringFormatExtension(object format, object arg0, object arg1, object arg2, object arg3) : this(format, arg0, arg1, arg2) { values.Add(arg3); }
    public StringFormatExtension(object format, object arg0, object arg1, object arg2, object arg3, object arg4) : this(format, arg0, arg1, arg2, arg3) { values.Add(arg4); }
    public StringFormatExtension(object format, object arg0, object arg1, object arg2, object arg3, object arg4, object arg5) : this(format, arg0, arg1, arg2, arg3, arg4) { values.Add(arg5); }
    public StringFormatExtension(object format, object arg0, object arg1, object arg2, object arg3, object arg4, object arg5, object arg6) : this(format, arg0, arg1, arg2, arg3, arg4, arg5) { values.Add(arg6); }
    public StringFormatExtension(object format, object arg0, object arg1, object arg2, object arg3, object arg4, object arg5, object arg6, object arg7) : this(format, arg0, arg1, arg2, arg3, arg4, arg5, arg6) { values.Add(arg7); }
    public StringFormatExtension(object format, object arg0, object arg1, object arg2, object arg3, object arg4, object arg5, object arg6, object arg7, object arg8) : this(format, arg0, arg1, arg2, arg3, arg4, arg5, arg6, arg7) { values.Add(arg8); }
    public StringFormatExtension(object format, object arg0, object arg1, object arg2, object arg3, object arg4, object arg5, object arg6, object arg7, object arg8, object arg9) : this(format, arg0, arg1, arg2, arg3, arg4, arg5, arg6, arg7, arg8) { values.Add(arg9); }

    DependencyProperty AddBindingTo(FrameworkElement fe, MultiBinding binding)
    {
        var dp = DependencyPropertyDepot.AllocateNewPropertyFor(fe);
        binding.Bindings.Add(new Binding() { Mode = BindingMode.OneWay, Source = fe, Path = new PropertyPath(dp) });
        return dp;
    }

    public override object ProvideValue(IServiceProvider serviceProvider)
    {
        var targetProvider = (IProvideValueTarget)serviceProvider.GetService(typeof(IProvideValueTarget));
        if (targetProvider == null)
            return null;

        var targetObj = targetProvider.TargetObject;
        // thankfully stolen from Thomas Levesque's blog
        if (targetObj != null && targetObj.GetType().FullName == "System.Windows.SharedDp")
            return this;

        var targetObjFE = (FrameworkElement)targetObj;

        var result = new MultiBinding()
        {
            Converter = new StringFormatConverter(),
            Mode = BindingMode.OneWay
        };

        foreach (var v in values)
        {
            if (v is MarkupExtension)
            {
                var b = v as Binding;
                if (b != null)
                {
                    result.Bindings.Add(b);
                    continue;
                }

                var bb = v as BindingBase;
                if (bb != null)
                {
                    targetObjFE.SetBinding(AddBindingTo(targetObjFE, result), bb);
                    continue;
                }
            }

            if (v is System.Windows.Expression)
            {
                DynamicResourceExtension mex = null;
                // didn't find other way to check for dynamic resource
                try
                {
                    mex = (MarkupExtension)rrconverter.ConvertTo(v, typeof(MarkupExtension)) as DynamicResourceExtension;
                }
                catch (Exception)
                {
                }
                if (mex != null)
                {
                    targetObjFE.SetResourceReference(AddBindingTo(targetObjFE, result), mex.ResourceKey);
                    continue;
                }
            }

            // fallback
            result.Bindings.Add(new Binding() { Mode = BindingMode.OneWay, Source = v });
        }

        return result.ProvideValue(serviceProvider);
    }
}