I'm running Ubuntu 18.04.2 LTS with the XFCE 4.12 desktop (Xfwm4 window manager) on an ASUS ROG laptop. The primary screen is 2560x1440 joined to the laptop's own 1920x1080.

Small but nagging problem unlocking a session after it locks automatically while I'm having coffee. As I return to the laptop the screen contains one single widget, the unlock dialog, unsurprisingly. The problem is that, in most cases, its password input field does not have keyboard focus, nor does it get focus by a single mouse click. Nothing happens when clicking the password field.

Restoring keyboard focus requires three (3) mouse clicks. All three are necessary.

1. Click the username drop-down
2. Select the current user
3. Click the password field

At step 2 the dialog sometimes disappears and leaves a screen containing nothing but background. I solve this by randomly pressing some of the function buttons in frustration, perhaps F8. The dialog appears again.

At other times, after step 2, the dialog jumps to a different location on the screen.