After collaborating with another consultant to develop a solution to make the PO Line Purchase Account required during Purchases Order Entry I decide to make this available for general use "AS IS" with no warranties. You can download the .dll here. This has only been tested with GP v10.
This wasn't as simple as just making the field required with Modifier since the Purchasing Item Detail Entry window, on which the field is located, does not have to be loaded during PO Entry. We accomplished the same thing with VBA but decided that the Visual Studio Toolkit for GP was a better option. If you want the VBA code just shoot me an e-mail and I'll send that to you.
The customization works like this:
During PO Entry, before you lose focus from a PO Line for which a Purchases Account was not entered or for which there was not a default value the system will notify you accordingly and stop you from continuing.
This customization will open Purchasing Item Detail Entry and then prevent the window from being closed or the record from being saved until the Purchases Account field is populated.
It's pretty simple but there were a few challenges we had to overcome. Now, you don't have to! If you do use it or just check it out leave me a comment and let me know what you think.