printSelection

Print the drawing: the selection if there is one, otherwise the page.

Not window.print(). The editor is a component on somebody's page, and the host window's print view is that whole page — headers, navigation, the article the canvas is embedded in, and a canvas element that a print stylesheet cannot usefully lay out. What the user asked to print is the drawing, so the drawing is what is rendered: the same SVG the exporter produces, alone in a hidden same-origin frame that is printed and then thrown away.

Returns false when there was nothing to print or no DOM to print it in; the menu item disables itself on the same condition, so this is the belt-and-braces case rather than the normal one.