Hi Tina,
I have modified the solution to the way the validation is done in our application (we are using IDataErrorInfo interface instead of throwing ValidationExceptions).
I was able to reproduce the issue I am facing.
As you can see from attached screenshot if enter value greater than $250 into masked box you will get the error displayed next to the control in red.
Also if you hover the control with mouse the tooltip is showng the same error.
What we need is to keep the tooltip but get rid of the Error text next to the control. The screen I am working on is too busy and there is simply no space for the validation error.
Unfortunately I cannot attach the project so I am posting relevant code here:
MainWindow.xaml
DataValidationViewModel.cs