Form vlidations don't work when included in gridcells

Hello,

When the form items are included in gridcells, the validations are disabled.
So the submit is done even if fields are empty or invalid.

Here is my code :

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Thank you for your help

Reproduce the supplied Form with FormValidator, Grid/GridCell, FormItem, TextInput, NumericStepper, HGroup, and CheckBox controls. Start by tracing how FormValidator finds controls nested in GridCell and verify the required, string, and checkbox cases. Done means empty or invalid fields prevent submission as they do outside the grid.

Written by the indexing model from the issue text.