Martin Pěnkava

Minor question how about make MvxAppStart with ConfigureAwait(false) or it's bad idea?

> This won't work on iOS. Will throw a NSInternalInconsistencyException, since startup didn't finish before Window.MakeKeyAndVisible() was called. @Cheesebaron Now you mean question about ConfigureAwait(false)?

> This won't work on iOS. Will throw a NSInternalInconsistencyException, since startup didn't finish before Window.MakeKeyAndVisible() was called. @Cheesebaron No this works. I did not change anything in RunAppStart method...

+1 for support WinUI 3.0, it looks cool.

@rusanov-vladimir I looked at this problem and I can reproduce only if BackgroundColor in your Header object is null. But if whole object Header is null it works well. So...

When I tested implementation of `return default(System.Drawing.Color)` on Android platform in Playground.Android project. Background color has been set as default not `Black`. Not sure how other platforms.

This is how it [looks](https://ibb.co/n80JR1m). With: ``` ColorHolder = new ColorHolder() { BackgroundColor = null }; local:MvxBind="BackgroundColor NativeColor(ColorHolder.BackgroundColor);" ``` No exception and no black color.

I tried set custom color and binding null and you are right it's fully transparent. I think it's not worse than before and problem with throwing exception is solved.

Your idea with set current color is on Android platform possible but probably not for other platforms. We have [HERE](https://github.com/MvvmCross/MvvmCross/blob/11798c97af610624c8054dd2302d5d9cb747f386/MvvmCross.Plugins/Color/Platforms/Android/BindingTargets/MvxViewBackgroundColorBinding.cs#L20) and [HERE](https://github.com/MvvmCross/MvvmCross/blob/11798c97af610624c8054dd2302d5d9cb747f386/MvvmCross.Plugins/Color/Platforms/Android/BindingTargets/MvxTextViewTextColorBinding.cs#L20) information of current color.

@martijn00 @rusanov-vladimir @Cheesebaron And what about add code below [HERE](https://github.com/MvvmCross/MvvmCross/blob/11798c97af610624c8054dd2302d5d9cb747f386/MvvmCross/Binding/Combiners/MvxValueConverterValueCombiner.cs#L82). ``` if (sourceValue == null) { value = MvxBindingConstant.DoNothing; return true; } ``` It's possible make it only for MvxColorValueConverter...