SampleApp rebuilds even if no changes

[michael-hawker]

Describe the bug

If you run the sample app with F5, and then later after closing it hit F5 again without making code changes, VS rebuilds the SampleApp project. ☹

Steps to Reproduce

Steps to reproduce the behavior:

1. Clone Repo
2. Build and Run Sample App
3. Close Sample App
4. Hit F5 Again

Expected behavior

Sample App Launches 'immediately'

Actual behavior

VS rebuilds Sample App Project and then runs.

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] May 2020 Update (19041)
- [ ] Insider Build (build number: )

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: )
- [x] 2019 (version: 16.6.0) 
- [ ] 2019 Preview (version: )

Additional context

Add any other context about the problem here.

[mrlacey]

I was investigating this problem in another app and so thought I'd contribute the fix here too.

The issue was that some .xaml files were configured to be copied to the output file. However, this was not needed and the build process already copied binary compiled versions of those files (.xbf) to the same location. The build process was looking for changes and missing output files, saw the .xaml files weren't in the output location and so triggered a rebuild to put them there.
As these xaml files did not need to be copied to the output directory I simply changed this property for the relevant files and now the app can be relaunched for debugging without requiring compilation if nothing has changed.