tech ▁made ▁the ▁Unix ▁version ▁of ▁the ▁Qt ▁libraries ▁available ▁under ▁the ▁G PL ▁in ▁addition ▁to ▁the ▁Q PL ▁which ▁elimin ated ▁the ▁concerns ▁of ▁the ▁Free ▁Software ▁Foundation . ▁T roll tech ▁continued ▁to ▁require ▁lic enses ▁for ▁developing ▁propriet ary ▁software ▁with ▁Qt . ▁The ▁core ▁libraries ▁of ▁K DE ▁are ▁collect ively ▁lic ensed ▁under ▁the ▁GNU ▁L G PL ▁but ▁the ▁only ▁way ▁for ▁propriet ary ▁software ▁to ▁make ▁use ▁of ▁them ▁was ▁to ▁be ▁developed ▁under ▁the ▁terms ▁of ▁the ▁Qt ▁propriet ary ▁license . ▁ ▁Starting ▁with ▁Qt ▁ 4 . 5 , ▁Qt ▁was ▁also ▁made ▁available ▁under ▁the ▁L G PL ▁version ▁ 2 . 1 , ▁now ▁allowing ▁propriet ary ▁applications ▁to ▁leg ally ▁use ▁the ▁open ▁source ▁Qt ▁version . ▁ ▁See ▁also ▁ ▁K DE ▁Platform ▁ ▁Com parison ▁of ▁X ▁Window ▁System ▁desktop ▁environments ▁ ▁References ▁ ▁External ▁links ▁ ▁The ▁K DE ▁website ▁K DE . News , ▁news ▁announ c ements ▁K DE ▁community ▁for ums , ▁the ▁official ▁forum ▁board ▁Planet ▁K DE , ▁blog ▁aggregate ▁K DE ▁w ik is ▁K DE ▁Local ization ▁K DE - App s , ▁K DE ▁and ▁Qt ▁software ▁repository ▁K DE - Look ▁K DE - Files ▁▁▁ ▁Category : 1 9 9 8 ▁software ▁Category : Free ▁desktop ▁environments ▁Category : K DE ▁software ▁Category : Un ix ▁window ing ▁system - related ▁software ▁Category : Util ities ▁for ▁Linux ▁Category : Util ities ▁for ▁mac OS ▁Category