Bug 1649202 will integrate a print preview in the tab modal print UI but printUtils.js is currently only set up to handle one print preview at a time.

We can likely get a preview in that bug by closing any existing print modals when a new one is opened but getting multiple open at once will take some refactoring or a rewrite of the printUtils.js functionality.

This depends on the updated preview API which will take print settings as an argument rather than pulling the current saved settings.

If we can't use the new frameLoader API we could potentially serialize the settings we have to JSON and pass them through https://gist.github.com/mstriemer/7ab51d4c2cba4d7ad22add6f6a76899c

The frameLoader API is on its way, we should be able to use that soon.

https://hg.mozilla.org/mozilla-central/rev/2d279a8a5787

Comment on attachment 9172832 [details]
Bug 1653319. Use the new FrameLoader.printPreview API in the frontend. r=mstriemer,emalysz,sfoster

Beta/Release Uplift Approval Request

• User impact if declined: Print settings not applied correctly to preview or paper output.
• Is this code covered by automated tests?: No
• Has the fix been verified in Nightly?: Yes
• Needs manual test from QE?: No
• If yes, steps to reproduce:
• List of other uplifts needed: None
• Risk to taking this patch: Medium
• Why is the change risky/not risky? (and alternatives if risky):
• String changes made/needed:

Comment on attachment 9172832 [details]
Bug 1653319. Use the new FrameLoader.printPreview API in the frontend. r=mstriemer,emalysz,sfoster

Approved for 81.0b6.

https://hg.mozilla.org/releases/mozilla-beta/rev/665ab4ca9830