Code:
[root@kindle bin]# xwininfo -root -children | grep matchbox
0x1400257 "L:KB_N:application_ID:matchbox-keyboard": () 758x341+0+0 +0+0 MapState=IsViewable
So apparently it works, but I can't see it. I tried launching the keyboard alone, same deal. Is there some way to force it to the front?