Android AVD keyboard input not working all the time on xUbuntu OS

You see, the main case is Android Emulator Window don't have the proper focus even when you click on it. Yes, you can do any touch-operations, but frame still appears non-focused.

I've found a workaround for that:

1. Go to your Window Manager
2. Find Focus tab
3. Change Focus Model -> "Focus follow mouse"
4. (Optional) Apply proper delay (I've put it to the lowest value)
5. Disable "Automatically raise windows when they receive focus" option bellow.

Now, whenever you hang your cursor above the emulator window it'll gain correct focusing state and you'd be able to use you keyboard just fine.

If you open the Window Manager Tweaks menu and go to Focus tab then you can select the Do nothing option under the When a window raises itself. This worked for me multiple times. (Different ubuntu verions)

Mine was caused because I was using a keyboard layout different from English US (I could notice strange symbols when I typed in the emulator settings screen - the three dots as OP pointed out). After I changed my keyboard layout the problem is gone.