Expression Builder in the Transformation Editor does not allow negative numeric constant values

Unable to input negative constant values into the expression editor. no errors or warnings occur when attempting. When pressing the hyphen key to input a negative, nothing is entered as a value. This affects TIMESTAMPADD() as an example. Without being able to enter a negative number, there is not a way to subtract from a date/time/timestamp value.

Workaround is to manually enter the negative value into the transformation SQL.