[WPF] StackLayout VerticalOptions = LayoutOptions.End is not working

[flyingxu]

Bug report best practices: https://github.com/xamarin/Xamarin.Forms/wiki/Submitting-Issues

Description

In StackLayout, VerticalOptions = LayoutOptions.End is not working

Steps to Reproduce

1. Edit Xamarin.Forms.Controls/GalleryPages/StackLayoutGallery.cs as below:

    var stack = new StackLayout { VerticalOptions = LayoutOptions.End};

change to LayoutOptions.End

Button b1 = new Button { Text = "Boring", HeightRequest = 100, MinimumHeightRequest = 50 };

HeightRequest is changed to 100 (make it shorter)

Button b4 = new Button { Text = "Meh", HeightRequest = 100, MinimumHeightRequest = 50 };

again HeightRequest is changed to 100 (make it shorter)
2. Run the project of Xamarin.Forms.ControlGallery.WPF, then select StackLayout Gallery - Legacy
3. Check the layout of the StackLayout

Expected Behavior

Buttons should be bottom-aligned

Actual Behavior

Buttons are top-aligned

Basic Information

• Version with issue: 3.0.Pre3
• Platform Target Frameworks:
  • WPF: 3.0.pre3

Screenshots

[mohachouch]

I started to investigate this issue.

I think I have found the error (see screenshot)

I will continue to validate this solution and I will make a pull request in the next days.

Thanks :)