This option will show only when you select the "Cascade" global extension (see Global extension).
When you select that particular extension, every procedure on your app will populate with a local extension, therefore you mustn't use the PrintWindow button as control template, but you just need to tweak the local extension if necessary.
As you don't populate a visible button on every window, your user still need a way to call the PrintWindow report. This way would be pressing the global hot key defined here.
When you press the key defined here on any window on your program, the PrintWindow report will be immediately executed. You have to instruct your users on which key that would be.