It’s not uncommon to want to study more than one part of a PDF document at once. When you’re researching, you may need to refer to references, endnotes, and other sections while you are reading the main body.

There appears to be a curious limitation in macOS AppKit which makes it difficult for a user to see any open document in two or more windows at once: AppKit won’t let you open a document more than once at a time. Test this in Preview, or previous versions of Podofyllin, for instance, and when you try opening the same file, the app just thrusts the existing document window at you. This is even true with tabs, although browsers like Safari are quite content to open the same webpage in different windows or tabs.

One solution is to support split views in a single document window. For Podofyllin, that wouldn’t work, as it already has four views side-by-side, and splitting the main PDF view further would become unmanageable, forcing you to make that window very large when you wanted to use the feature.

The solution that I have implemented in this new beta release of Podofyllin is to open an ancillary PDF view in another window. To use this, bring the main document window to the front, and use the Open PDF command in the Window menu. You’ll then get exactly the same document (using the same source, so sparing of memory) displayed in a separate window.

There is one slight twist here: if you’re going to use this feature, you should normally turn off showing thumbnails, because of the macOS bug which will link their scrolling. Unfortunately it also affects these ancillary windows.

You can use contextual, View and Go menus to change the display of ancillary windows, just as you can for the main document window.

To help you distinguish ancillary windows from the main document window, the former are displayed and listed with a prefatory ❗️, and source windows are marked with ‼️.

I hope that you find this unusual feature of use.

Version 1.0b5 of Podofyllin is available from here: podofyllin10b5
and from Downloads above.

Thanks to Mark @mwra for suggesting multiple view support.