FIJISettingsViewer: call check_change() on lfsr_mask changes to indicate unsaved changes

bin/Tk/FIJISettingsViewer.pm

@@ -1088,7 +1088,11 @@ sub _add_fiu_widgets {
     $mask_entry->configure('-text' => sprintf("0x%x", $fiu->{'FIU_LFSR_MASK'}));
     $mask_entry->configure(
         '-validate'        => 'key',
-        '-validatecommand' => [\&_validate_fiu_entry, $self, 1, $mask_entry, 'FIU_LFSR_MASK', $i],
+        '-validatecommand' => sub {
+            $self->_validate_fiu_entry(1, $mask_entry, 'FIU_LFSR_MASK', $i, $_[0]);
+            $self->_check_change();
+            return 1;
+        },
     );
     $mask_entry->{'displaygroup'} = DISPLAYGROUPS_FIU_KEY;
     $mask_entry->{'key'}          = "FIU${i}_LFSR_MASK";