View: list. Having ocr a pdf - and highlighted some text and zoom-in and zoom-out, not necessarily in that order - I then clicked a different entry entirely but the pdf remained in the viewer. I clicked other entries but the issue persisted. The only way I got rid of it was to quit DT3 and relaunch.
Thanks for the bug report, it’s a known issue that will be fixed by beta 5. Closing the window and opening a new window should be also sufficient.