Hi Laurent,
We already answered this question in your bug report, but I will post the same answer here so others from the community will be aware.
This is a bug in our
RadMaskedTextInput. We logged it in our
PITS where you can track its status. However, we cannot currently promise an estimated time for the fix. Thank you for your understanding.
All the best,
Pavel R. Pavlov
the Telerik team