I just received one of these very cool 7″ touchscreens for the Raspberry Pi: https://www.raspberrypi.org/products/raspberry-pi-touch-display/
I have the default logon prompt when my Pi starts up, so first challenge is, how do you logon without a real keyboard attached, without having to disable the logon? There are a number of onscreen keyboards available – based on this thread I installed florence:
sudo apt-get install florence
and then edited /etc/lightdm/lightdm-gtk-greeter.conf adding ~a11y; for the Accessibility icon on the logon screen, and keyboard=florence so it appears in the menu.
The keyboard now appears, but as soon as I press a key it disappears. From this thread, installing at-spi2-core appears to fix the issue:
sudo apt-get install at-spi2-core
This seems to fix the keybaord not disappearing, but not having any luck getting characters to appear in the username/password fields. Still some investigation to do on this one.