[Suggestion] add overload to pass Brush as background/foreground as well

[amir1376]

Hi dear @alexstyl , thank you so much for your effort in building this amazing project.
I’d like to suggest a feature that allows users to pass a Brush (in addition to Color), as this is needed in some designs.

For example, what if I want to use a Button (or Checkbox) widget but need to apply a gradient background like these?

[alexstyl]

Love the idea. Will make sure to include it in a future version