Describe the bug

It appears in certain cases with certain app themes (light vs. dark) the selection highlight on the InfiniteCanvas Toolbar isn't appearing correctly. This makes it difficult to understand the current state of a textbox within the canvas. See screenshots below.

• Is this bug a regression in the toolkit? If so, what toolkit version did you last see it work:

Steps to Reproduce

Steps to reproduce the behavior:

1. Go to InfiniteCanvas sample in Sample App
2. Add a TextBox
3. Make it Bold
4. Change Themes

Expected behavior

Should see blue selection for button in all scenarios/themes.

Screenshots

If applicable, add screenshots to help explain your problem.

From Dev:

From Store:

(Note ignore if you see Italic selected as well, that was fixed as part of #3118.)

Environment

NuGet Package(s): 

Package Version(s): 

Windows 10 Build Number:
- [ ] Fall Creators Update (16299)
- [ ] April 2018 Update (17134)
- [ ] October 2018 Update (17763)
- [ ] May 2019 Update (18362)
- [x] Insider Build (build number: 19592)

App min and target version:
- [ ] Fall Creators Update (16299)
- [ ] April 2018 Update (17134)
- [ ] October 2018 Update (17763)
- [ ] May 2019 Update (18362)
- [ ] Insider Build (xxxxx)

Device form factor:
- [ ] Desktop
- [ ] Xbox
- [ ] Surface Hub
- [ ] IoT

Visual Studio 
- [ ] 2017 (version: )
- [ ] 2019 (version: ) 
- [ ] 2019 Preview (version: )

Additional context

Not sure if this is an Insider or Release build type issue? Is anyone else seeing this?