After update to Android Studio Bumblebee this issue start happening.
Seems like all clicks are long clicks (or right clicks), the menu is triggered all the time even if I click left side.
I have cleared the cache, deleted the emulator, updated the emulator, but after on or two minutes the issue starts happening. The issue is solved if I do a cold boot too, but two minutes after the issue starts again.
I had this same issue, and after updating the Android emulator to the latest stable version (31.3.10-8807927), I have not experienced this anymore.
I did the update via Android Studio's "Check for updates".