An idea: a transparent toolbar, so that you can see a small part of the document (the part where the toolbar is, you could see all of that part of the document if you have a small number of toolbar items). Reproducible: Always
Thanks for caring about Okular and taking time to report this wish item :-) This deviates from standard KDE UI practices and I do not see a compelling reason to implement this only in okular so i'm closing the wish. Feel free to pursue greater consensus amongst the kde developers (kde-usability mailing list might be a good starting forum) for this and all the other UI/UX improvements you are suggesting to Okular and if there is an agreement that they make sense for the greater global KDE applications someone might implement those for all of the KDE applications globally.