drag and drop on sequenced editable list

How to reproduce :

1. Go to "Accounting" > "Customers" > "Customer Invoices"

2. Create a new Invoice

3. Set the customer

4. Add a new invoice line, with any of the products

5. Add a second invoice line, with any of the products, and, while editing, try to drag and drop the line to put it before the first line

6. A wild pop-up appears, warning you that you are leaving the page and asking you if you want to continue, losing your changes (But, wait, am I leaving the page ? No I am not !). Whatever you choose (Ok or Cancel), the result will be the same: an empty or gray line.

The fix is maybe to disable the drag and drop while editing.