XamlBindingHelper not returning right values

[carldebilly]

Description

When using XamlBindingHelper.Convert() to test the conversion of specific structures, there are noticeable behavioral differences between Windows (WinUI) and Uno. The expected behavior is that conversion of structures to string using Convert(typeof(string), value) should produce a format similar to .ToString() and should also support reconversion back to the original structure.

Below is a comparison table showing results on each platform and reconversion support for Uno:

Structure	Windows Result	Uno Result	Reconversion Support (Uno)
Matrix(1, 2, 3, 4, 5, 6)	1,2,3,4,5,6	1,2,3,4,5,6	✅ Yes
Thickness(1, 2, 3, 4)	1,2,3,4	[Thickness: 1-2-3-4]	❌ No
CornerRadius(1,2,3,4)	1,2,3,4	TopLeft: 1, TopRight: 2, BottomRight: 3, BottomLeft: 4	❌ No
Duration(TimeSpan.FromSeconds(1))	00:00:01	00:00:01	✅ Yes
Duration.Automatic	Automatic	Automatic	✅ Yes
Duration.Forever	Forever	Forever	✅ Yes
GridLength(1, GridUnitType.Auto)	Auto	Auto	✅ Yes
GridLength(1, GridUnitType.Star)	1*	*	✅ Yes
GridLength(1.5, GridUnitType.Star)	1.5*	1.5*	✅ Yes
GridLength(1, GridUnitType.Pixel)	1	1.0px	✅ Yes BUT WEIRD
GridLength(1.5, GridUnitType.Pixel)	1.5	1.5px	✅ Yes BUT WEIRD
Point(1, 2)	1,2	[1, 2]	❌ No
Rect(1, 2, 3, 4)	1,2,3,4	1,2,3,4	✅ Yes
Size(1, 2)	1,2	1,2	❌ No
Color (Colors.Beige)	#FFF5F5DC	#FFF5F5DC	✅ Yes

Issues to Address

1. Conversions for Thickness and CornerRadius do not support reconversion to the original structure on Uno.
2. Conversion of Point results in a different format ([1, 2]) on Uno and does not support reconversion.
3. Desired format alignment between Uno and Windows for GridLength with pixel unit (1 vs 1.0px).

The goal is for Uno to properly support reconversion to the original structure, and ideally, to align output format with Windows (though this is less critical).

Expected behavior

Uno should be able to convert forward and convert backward to string for those structs. (to and from string).

How to reproduce it (as minimally and precisely as possible)

No response

Workaround

Not using the XamlBindingHelper

Works on UWP/WinUI

Yes