▁for ▁the ▁popular ity ▁of ▁T cl ▁in ▁pro l ific ▁areas ▁of ▁use ▁such ▁as ▁in ▁Unix ▁testing , ▁where ▁Ex pect ▁was ▁( and ▁still ▁is ▁today ) ▁employed ▁very ▁successfully ▁to ▁autom ate ▁tel net , ▁ssh , ▁and ▁serial ▁sessions ▁to ▁perform ▁many ▁repet itive ▁tasks ▁( i . e ., ▁script ing ▁of ▁formerly ▁interactive - only ▁applications ). ▁T cl ▁was ▁the ▁only ▁way ▁to ▁run ▁Ex pect , ▁so ▁T cl ▁became ▁very ▁popular ▁in ▁these ▁areas ▁of ▁industry . ▁ ▁T ile / T tk ▁T ile / T tk ▁is ▁a ▁styles ▁and ▁them ing ▁widget ▁collection ▁that ▁can ▁replace ▁most ▁of ▁the ▁widget s ▁in ▁T k ▁with ▁variants ▁that ▁are ▁truly ▁platform ▁native ▁through ▁calls ▁to ▁an ▁operating ▁system ' s ▁API . ▁Th emes ▁covered ▁in ▁this ▁way ▁are ▁Windows ▁XP , ▁Windows ▁Classic , ▁Qt ▁( that ▁hook s ▁into ▁the ▁X 1 1 ▁K DE ▁environment ▁libraries ) ▁and ▁Aqu a ▁( Mac ▁OS ▁X ). ▁A ▁theme ▁can ▁also ▁be ▁constructed ▁without ▁these ▁calls ▁using ▁widget ▁definitions ▁supp lement ed ▁with ▁image ▁pix maps . ▁Th emes ▁created ▁this ▁way ▁include ▁Classic ▁T k , ▁Step , ▁Alt / Re v ital ized , ▁Pl ast ik ▁and ▁Ker am ik . ▁Under ▁T cl ▁ 8 . 4 , ▁this ▁package ▁is ▁known ▁as ▁T ile , ▁while ▁in ▁T cl ▁ 8 . 5 ▁it ▁has ▁been ▁fol ded ▁into ▁the ▁core ▁distribution ▁of ▁T k