I often use AE text boxes and catch the FKey value when they type past the end of a field.
It'd be really nifty if BR! had another attribute like A or E that returned an FKey value no matter what they typed, any keypress that occurs in said textbox. left arrow, right arrow, backspace, etc.
"A new leading attribute "^user_entry", returns control to the program upon the cursor entering a field. This does not apply to fields given initial focus by INPUT processing, such as with CURFLD or the first field of a FIELDS operation."