The implementation for the X mask would accept any printable
character. Since that includes the blank character, there was no
difference in behavior between the requiring X and optional x: both
would allow the input to be unset, i.e. blank.
This change should be seen in conjunction with the doc improvement
da0af1e.
[ChangeLog][QtWidgets][QLineEdit] Inputmask X character now requires non-blank input.
Fixes: QTBUG-76320
Change-Id: I3e0363e9be5c13373a157cce69c99379615b5829
Reviewed-by: Volker Hilsheimer <volker.hilsheimer@qt.io>
Reviewed-by: Shawn Rutledge <shawn.rutledge@qt.io>
95689c645f