If PDF.js has no way to intercept the Ctrl+P in this case (probably not per last line of comment 3), then any hypothetical intervention here would probably want to happen at a higher level, e.g. as some analysis that gets run when Firefox handles a Ctrl+P/File|Print operation in an outer document and is getting ready to spawn a print dialog. --> Reclassifying to Toolkit|Printing
Bug 1906967 Comment 6 Edit History
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If PDF.js has no way to intercept the Ctrl+P in this case (and probably it has no way, per last line of comment 3), then any hypothetical intervention here would probably want to happen at a higher level, e.g. as some analysis that gets run when Firefox handles a Ctrl+P/File|Print operation in an outer document and is getting ready to spawn a print dialog. --> Reclassifying to Toolkit|Printing