DrawingContextImpl
- Alpha support missing as SkiaSharp does not expose this
- Gradient Shader caching?
- Pen Dash styles

Formatted Text Rendering 
- Minor polish

Linux
- Need gpu platform implementation

macOS
- Need gpu platform implementation

Android
- Not tested at all yet

iOS
- Not tested at all yet

General
- Get Skia Unit Tests passing (most of the issues are related to antialiasing)