Xamarin.forms: [UWP] does not render Frame CornerRadius

[varyamereon]

Description

UWP does not render Frame with CornerRadius, instead it reverts to square corners. Control is rendered correctly on iOS and Android. https://bugzilla.xamarin.com/show_bug.cgi?id=56914 refers.

Steps to Reproduce

1. Add frame to Xamarin.Forms project.
2. Set corner radius > 0
3. Run project on UWP. Frame ignores corner radius property.

Expected Behavior

Xamarin.Forms should render a UWP Border control with the background color set inside and corner radius set as appropriate.

Actual Behavior

A Border control is rendered correctly but inside another element which shares the same background color, making the control appear like it has square edges.

Basic Information

• Version with issue: Xamarin.Forms 3.0.0
• Last known good version: n/a
• IDE: Visual Studio 2017 15.7.2
• Platform Target Frameworks:
  
  
  
  • UWP: 17134
  
  
• Affected Devices: Tested on Surface Book.

Screenshots

Reproduction Link

https://github.com/varyamereon/FrameIssue

[MartinZikmund]

May I take this one? @jassmith @varyamereon @pauldipietro

[JTOne123]

If we change bg color a few times and set default bg again, it causes the issue.

Steps to reproduce
1) Set the backbround color
2) Set the default backround color