Canon PIXM MX300 Series User Manual page 60

Printing begins.
Note
The message asking to confirm the position of the Paper Thickness
Lever may be displayed. Follow the on-screen instructions if the
message is displayed.
To cancel a print job in progress, press the Stop/Reset button on
the machine or click Cancel Printing on the printer status monitor.
To display the printer status monitor, click Canon XXX Printer
(where "XXX" is your machine's name) on the taskbar.
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