Wpf textbox validating radiocarbon dating of fossils taken from caves on islands along
To do this, we are going to create a style that replaces the default error template.
Errors in parentheses to indicate that it's an attached property as opposed to a property of the Text Box. This allows for creating templates that appear to change the control being adorned.
And if you start with a reasonable default in the field, any changes should be assumed to be intentional, and so if invalid need correcting by the user.
An exception to this, though, would be cases where an empty field is invalid by itself, but can be extrapolated to a reasonable default, in which case faded-out and/or italicized text within to indicate the default is useful.
By adding an additional border (with a Background="Red" Opacity="0.2"), we can create the look below, which is much more pronounced.
When the additional border with a background is added, the Tool Tip on the Text Box never displays since the adorner captures the hover.