The File | Print | All | Print to PDF function works well, but is slow if there are a lot of structures loaded, and the UI provides no feedback on the process. The process also seems to lock the application suggesting that the process is running on the event dispatch thread, because the application becomes unresponsive if the process is long-running.
The process could use a progress bar to provide some feedback. Adding a cancel button to the progress bar would allow the user some control over processes that are very long-running.
I had 1086 structures loaded from a SMILES file, and I wanted to print them for data archival purposes. The print to PDF process (using MarvinView 19.12.0) took a minute or two to complete. There was no feedback, and I was unsure if it was working, or if something was wrong. The only way I could tell something was happening was that the CPU meter showed activity, and I could see the file size of the PDF file increasing in the Windows File Browser.
Thank you for this request, I have answered in the bug report topic, you have created.