Black keyboard randomly appearing, sometimes displaying my login passcode

Question

iPad 3, iOS 8.1.1 (12B435).
As the title says.  A black keyboard randomly appears, sometimes displaying my login passcode as four digits at the top left of the superimposed keyboard.  It happens any time, during any task (usually not entering text where the keyboard is required).  I always use a quality bluetooth keyboard and only occasionally use the screen keyboard for selecting eMoji characters.  This is achieved by hitting the relevant bluetooth keyboard button to call up the screen keyboard.
It's difficult to make the black random keyboard disappear.  The usual keyboard-call button doesn't do it, nor mostly does pressing the home button.  When I hit the home button, it works as it should, but the black keyboard stays on top and then half-covers the app icons. See two of the screenshots below, one which shows the (now-blanked-out)four-digit code enclosed in quotes.
I'm pretty concerned this is a security issue (and I'm far from being a paranoid person), especially since my login code (which I've changed) appeared for all to see.
Any ideas?  Thanks. :-)
Message was edited by: goltho: Screenshots added.

Answer 1

To attach a screen shot first move the insertion point ( blinking blue line) downtwo rows. Tap the tiny camera icon. Tap the center of the window that opens up. Tap choose file. Tap photo lubrary. Tap moments Chose image by tapping on it. Tap insert image. Unfortunately I don't know how to keep the black keyboard from appearing.
Edit. I see you figured it out without me. Well done.