You didn't ask for it, but I added in the ability to collect the full list of check numbers and amounts.
That is, on the popon, as the user enters check numbers and amounts, not only is the total of the check amounts shown in the "total" field, but a list of checks is stored in the checkList field. That field would normally be a hidden field (so you would change xtype= to type=), but it is purposely displayed here so you can see what it looks like.
If you really don't want that, and you don't want to input the check numbers, it's a fairly easy change.
An optimist sees the glass as half full.
A pessimist sees the glass as half empty.
A realist drinks it no matter how much there is.