don't set focus button for Android
don't set focus button for Android

koreader/koreader,mihailim/koreader,NiLuJe/koreader,poire-z/koreader,Frenzie/koreader,frankyifei/koreader,pazos/koreader,lgeek/koreader,chihyang/koreader,NickSavage/koreader,robert00s/koreader,apletnev/koreader,Markismus/koreader,Hzj-jie/koreader,mwoz123/koreader,houqp/koreader,poire-z/koreader,Frenzie/koreader,koreader/koreader,NiLuJe/koreader