kTableLabelTextAttrs top-level property
textAttrs of every table label: centred on its anchor both ways, the
width factor its own (bit 8), so a mirror can be undone by −1.
Implementation
final int kTableLabelTextAttrs = packTextAttrs(
h: TextJustifyH.centre, v: TextJustifyV.middle, overrideWidthFactor: true);