ID:260808
 
winget(client, id, "parent")


edit: and now that I think of it, getting a list of child nodes would be useful too.

winget(client, id, "children")

work-aroundish:
mob/verb/Get_Parent()
var/Control="output1"
world<<"The parent of <b>[Control]</b> is <b>[WingetParent(usr,Control)]</b>."

mob/verb/Get_Children()
var/Parent="default"
var/list/Children=WingetChildren(usr,Parent)
world<<"The <b>[Children.len]</b> Children on <b>[Parent]</b> are:"
for(var/v in Children) world<<"<b>[v]"


proc/WingetParent(var/Player,var/Control)
winset(Player,"[Control]","focus=true")
var/Parent=winget(Player,null,"focus")
return copytext(Parent,1,findtext(Parent,"."))

proc/WingetChildren(var/Player,var/Parent)
var/list/Params=params2list(winget(Player,"[Parent].*","size"))
var/list/Children=list()
for(var/v in Params)
var/Period=findtext(v,"."),Period2=findtext(v,".",Period+1)
if(Period && Period2) Children+=copytext(v,Period+1,Period2)
return Children