BlankFill resource

Description
This resource has effect only in 3270 mode.

When blankFill is True, the emulator will automatically convert trailing blanks in a field to NULs in order to insert a character, and when a character is typed into the middle of a field, it will automatically convert leading NULs to blanks so that input data is not squeezed to the left. This works around some of the quirkier behaviors of real 3270 terminals.