playout:SetTabs([tabs])
Pango layout will place content at the next tab position whenever it meets a Tab character (U+0009).
By default, tabs are every 8 spaces. If the tabs parameter is
omitted, the default tabs are reinstated. tabs is copied into
the layout; you must free your copy of tabs yourself.
Note that tabs and justification conflict with each other:
Justification will move content away from its tab-aligned
positions. The same is true for alignments other than
#PANGO_ALIGN_LEFT.