A. The programmers designed the "note" screen so it allows the user to view/add/remove the notes assigned without closing and opening the popup screen each time and for every PO. Let's say you have 30 items on the PO and each item has some kind of note assigned.
You can select an item click on the "Assign Note" button and view/add/remove notes. Click on the "Save" button to commit the changes to the note, but do not exit the "note" screen. Now you can go back to the PO screen and select the next item, the "Note" screen will refresh with the next item "Note" information.
You can even find a new PO without closing the "Note" form. This way it saves you time going from item to item and clicking on the "Note" button, saving and exiting the "Note" screen and clicking on the note button again. Currently the "Note" screen is using different data sessions and has to be saved independent of the PO.
If we would allow the notes to be updated in the "Add"/Edit" mode and the note would be saved, but changes to the PO cancelled afterword, we could have a problem with the data integrity.