Due to bug #595474 newer versions of android-studio depend exclusively on zenity even though it can use alternatives to it. Since I can't reopen the original bug I opened a new one, but the details are all there in bug #595474
Fixed, thanks! commit 285ca7ff8f5cee0f175ddd3f5600302139213530 Author: Jason Zaman <perfinion@g.o> Date: Sat Nov 5 10:44:31 2016 dev-util/android-studio: also depend on other notify tools, bug 598722 Package-Manager: portage-2.3.0