Onboard settings at 19.04 login screen

Hello,
I've customized onboard for gnome a little bit (Layout + Theme + stretch width up to 2880px), but after restart or lock screen onboard size is too tiny to enter password. My finger is like 9 buttons.

Also I see strange behaviour,
Anyway, onboard has not mine Layout + Theme.
By default in login screen onboard width is about 560 px.
If I change in /usr/lib/python3/dist-packages/Onboard/Config.py line "DEFAULT_WIDTH = 2000" then
- If in login screen at "Universal Access" "screen keyboard" checkbox is set by default then onboard width is about 560 px. And after chekbox enabling/disabling does not change onboard width.
- If in login screen at "Universal Access" "screen keyboard" checkbox is NOT set by default then after set, onboard appears with width is about 2000 px.

I will appreciate for any solution:
- change onboard default settings
- disable onboard at login screen ("show when unlocking the screen" not work)
- set up lightdm to autostart "onboard -s 2000x800"
- disable checkbox in login screen at "Universal Access" "screen keyboard" after login.
...

Anyway, thanks for the great on-screen keyboard!

PS.
Ubuntu Disco Dingo (development branch) 19.04
GNOME 3.31.91
lightdm 1.28.0
onboard 1.4.1-2ubuntu4
Settings->Displays->scale->200%
Dell Latitude 7285 (12.3-in. touch display)