Unable to change Style of ToolbarButton

[timunie]

Describe the bug
The Style for Toolbar Button does not change Background etc

To Reproduce
Create a Style and try different setters

Expected behavior
ToolbarButton should be more Styleable

Screenshots
If applicable, add screenshots to help explain your problem.

Environment(please complete the following information):

• latest alpha
• OS: [e.g. Win10 1803]
• Visual Studio [e.g. 2017 15.7.1]
• .NET Framework [e.g. 4.7.1]

Repo
If it's possible follow these guidelines for a good sample and I will most likely look at the issue sooner:

Additional context
I know the root cause and will provide a PR