Provide clear error feedback to the user

When attempting to create an EasyShare folder, when one doesn't fill the expiration date (which is mandatory) in the initial creation screen and click Create, there is no UI feedback that this mandatory field was forgotten. So you click Create but nothing happens. For other mandatory fields like the title its underline gets highlighted in red (which I also think is insufficient, there should be at least a transient popup saying "please fill mandatory values") but for the date field there's no underline to highlight.

by Florent Guillaume

This is currently happening when you try to edit a document, and add a description longer than 200char. You will not be able to hit Save at the end, but will be clueless of the reason why.

The field itself should assume a different UI before moving forward, and if you missed it and tried to click the create/submit/OK button at the end of the form, a clear message of what and where is the error should be contemplated there as well.

All scenarios should be reviewed, in order to define one unique and consistent solution, that covers the wider use cases of the platform.