Customisable pop-up messages to warn end users of bad input values

Description of the enhancement required:
Pop-up messages which can be customized to show error/ warning messages to end users
An example of the enhancement:
A user logs into Anaplan, goes to a dashboard and in one of the fields inputs a number. Based on a pre-defined rule, if the number that is input by the users goes beyond a specific value, then a warning message should appear
A story for why you want the enhancement:
In their capacity planning process, users work on the same set of data to make adjustments to system suggested supply plan. While making adjustments, if the user does allocation over or below the actual demand, then there should be an warning message given to the users. As of now, this is being managed through a line item which shows the error that the user has made.
You must be a registered user to add a comment. If you've already registered, sign in. Otherwise, register and sign in.