[lubuntu-users] Alt+(anyletter) and input box appears in upper right corner

[Harry Putnam]

Ubuntu with lubuntu (as guest, with openindiana (solaris) as host)

lsb_release -a
No LSB modules are available.
Distributor ID:	Ubuntu
Description:	Ubuntu 19.04
Release:	19.04
Codename:	disco

Using LXDE desktop

The above version and at least two previous have exhibited the
behavior described below:

When I press Alt + any letter key I get a small input box in the upper
right of base screen, the letter I last typed appearing in the input box. 

As a semi-long time user of lubuntu (mostly as vbox guest on this same
solaris (offshoot) host and being a long time user of xbindkeys using
an xbindkeys key binding scheme of:


   `Alt + (various)letter' 

to call various programs (from `xbindkeys'), the above phenomena
blocks my ability to use xbindkeys with my preferred bindings.

(Input box captures any letter I type with `alt' key held down)

I did not really track what else had changed when I first noticed the
phenomena and trying now to discover the source of the input box is
not doing well.

I'd like to turn the appearance of input box off but not having much
luck figuring out what is invoking it or what program it is part of.

Understand that my setup with lubuntu as vbox guest on same host and
using `xbindkeys' has worked just fine ' for many months, up until
maybe 2 mnths ago (or maybe 3 mnths)

Can anyone tell me what program is involved in the appearance of the
(unsolicited) input box? Or especially how to turn it off.