Here are some various feature suggestions.
1) If I am in the dictionary or on a flashcard, tapping anywhere on the screen where there is no writing will cycle the dictionary to the next dictionary in your priority list.
2) When saving flashcards, allow them to be saved per dictionary. So that when a flashcard session is run, the definition that is shown will be the one for which the flashcard was originally saved. (maybe it already works this way, but I was unable to verify that).
3) In the OCR, double tapping will resize the paragraph to the width of the window/device. This would be for OCR on the PDF or a photo.
4) If Pleco has been rebooted completely (not just bringing to the foreground), then if the flashcards are set to not prompt for category each time, then prompt for category. The idea is that once you are in a session you are likely to use the same category for saving your cards. However, a clean start likely means that the category selection is much more uncertain.
5) If you are in the reader already, have some sort of refresh from pasteboard button. In this way if during your session, the clipboard is updated, there will be a way to grab it.
6) An option in the reader that, once you save the flashcard, the dictionary bubble will disappear. The idea is that "yeah, I've looked, seen the definition, like it enough that I want to further review it later, time to get backt to reading".