Note the following facts

• SettingsCardWrapThreshold might never be reached because the minimum width of the window
• there is no minimum width for PART_HeaderPresenter
• HeaderPanel uses <ColumnDefinition Width="*" /> while the other columns use Auto.
• PART_ContentPresenter has no TextWrapping property, the header and description do

Therefore the header will always give way to the content, even if you set wrapping on a textblock in the content.

This combination can lead to very ugly resizing behavior. See:

SettingsCard Wrap Threshold

SettingsCard Wrap Fail

What can be a solution?

• Most basic: set a minimum width on the header. But then, the header might be shorter than this minimum width...
• (and/or) Add TextWrapping to the content. But then ColumnWidth * will still always give way to Auto. So it wouldn't fix it?