Pencil got a Black canvas after following the steps:
open pencil
draw some lines using the PEN tool
pressing keyboard CTRL and dragging the PEN tool… a black colour will cover the main drawing window
(no matter what colour I have selected on the colour panel, the canvas will be covered with a black colour)
Pencil behaves differently if you do not re-start it.
Some times on number 3, you will see a black colour blinking while dragging the tool, and the canvas will be ok
Ctrl+drag is used in conjunction with the PEN and BRUSH tools. It is going to change the “value of Feather” of that tool.
The lines will appear smooth if applying a high value of the Feather. If Feather is like near zero, these lines will have hard edges