Hi Derk-Jan,
Thanks for your interest on the testing results.
Perhaps we can do the bounce animation again if people hover the panel ?
Currently we are displaying the animation only for users that have not opened the panel before. We do this each time they enter the Media Viewer, but not when they move next/previous. I think that provides a good prominence level to allow discoverability without being too annoying. Most users will not even need this since we are providing multiple entry points (scroll, keyboard arrows, and chevron pointing up in the panel).
Moving the panel up on hover makes sense from a continuity perspective, my concern is that it may present issues if the user tries to click on specific targets (e.g., a link which is part of the title, the author name, or reuse icon on the right) and fails to do so because of the movement.
Having said that, we'll keep testing with users and explore design solutions to improve the issues we find, and what you suggest is worth considering if we need to make the panel more prominent.
So thanks for your feedback and interest on the project.
Pau