Ah, now I see the issue. Only one custom size can be defined at a time (at the machine). Unfortunately there doesn't appear to be a way around this, but I'll ask around with some of the developers.
Being able to store multiple custom sizes in the driver and at the machine makes a lot of sense. Thanks for the idea!
The bypass tray will always reset once the paper is removed from it. That's why every time you put a different size of paper in it it will ask to confirm the size. The bypass tray is specific for special size media.
I understand custom sizes can be entered in the driver, this isn't the issue. It's entering them in the machine. Eg: If you make up a custom size of 6x6" in the driver, and put 6x6" paper in the bypass/Tray 1 on the 7800, it will still ask you to input the size of the paper into the control panel on the machine itself. If you then send another job with a size of say 10x10", you will need to enter the custom size again.
Go back to doing the 6x6" size, once again, you have to re-enter the custom size into the control pannel. Saving sizes in the driver is easy, but only half the solution.
You can save them in the driver.
The attachment is from the user guide:
I have a Phaser 7800 and print a lot of custom sized work from tray 1. On the control panel when I put the stock in, I select "Add a new custom size" but it only lets me add one new custom size, and every time I need to put a different custom size into the machine it over-writes the one I just made.
Is there any way of entering multiple custom sizes into the control panel for tray 1?