Fixes AlternatingRowForeground not being applied

[thiago-cs]

Fixes AlternatingRowForeground not being applied when in Light theme.
Dark theme is OK.

Fixes #4140

Fixes AlternatingRowForeground not being applied when in Light theme.

PR Type

What kind of change does this PR introduce?

• Bugfix

What is the current behavior?

The AlternatingRowForeground is not applied when in Light theme because the default value for the dependency property DataGridRow.Foreground is #FFFFFFFF but the foreground brush itself under Light Theme is not. That causes the LOC # 1129 (see below) to always evaluate to false under Light Theme, which in turn leads to the AlternatingRowForeground brush to be ignored every time.
[1129] if (this.Foreground.Equals(defaultForeground))

What is the new behavior?

This commit removes LOC # 1129 for causing the undesirable behavior. It also simplifies the resulting code.

PR Checklist

Please check if your PR fulfills the following requirements:

• Tested code with current supported SDKs
• Pull Request has been submitted to the documentation repository instructions. Link:
• Sample in sample app has been added / updated (for bug fixes / features)
  • Icon has been created (if new sample) following the Thumbnail Style Guide and templates
• New major technical changes in the toolkit have or will be added to the Wiki e.g. build changes, source generators, testing infrastructure, sample creation changes, etc...
• Tests for the changes have been added (for bug fixes / features) (if applicable)
• Header has been added to all new source files (run build/UpdateHeaders.bat)
• Contains NO breaking changes

Other information

Tested in Windows 21H1 only.Tested in Windows 21H1 only.

Edit no. 1: Fix the number of the issue that this PR aims to solve.

[ghost]

Thanks thiago-cs for opening a Pull Request! The reviewers will test the PR and highlight if there is any conflict or changes required. If the PR is approved we will proceed to merge the pull request 🙌

[Rosuavio]

#4138 Included this change correct?

[thiago-cs]

#4138 Included this change correct?

Possibly.
I filed one issue and submitted its fix. Then I found the problem with the alternating row foreground, filed another issue and submitted another PR. Those two PR got merged (don't know why). My intention was to have 2 issues and two separate PR for better documentation/tracking.
The code summited to fix the alternating row foreground is the same.

[michael-hawker]

@thiago-cs you were submitting PRs from your fork's main branch. You need to create a new separate branch for each PR you submit. I believe we have some info on this in our Wiki.

We actually should have noticed this and had you fix it before submitting; merging from other forks mains can have issues if they're not 100% in sync with our main. But I think it's fine for this small PR, so we should be OK.

FYI @RosarioPulella @XAML-Knight

Considering the other PR contained both fixes, was approved, and merged. Then we can probably close this one.