Selecting books:
Multiple adjacent books can be selected with Shift+right/left arrow OR Ctrl+right/left arrow OR Ctrl+Shift+right/left arrow. How do I select multiple non-adjacent books?
In vertical lists (List view, Book Editor File browser etc) Shift+up/down arrows is used to select adjacent items and Ctrl+up/down arrows,Space is used to select non adjacent items.
Group by
Now the Group by button has been moved from the Context menu to the Search bar could it have a keyboard shortcut… no need for a default.
In dark mode, the Group by dividers are a rather indistinct, suggest they be off-white with dark grey text, full height of shelf with text top justified
Spine widths
Rather than the fraction in the spine width template, add a Fixed width spine checkbox. If checked activate a slider widget and let the user use it to set the width visually, and deactivate (grey out) the Spine width template widgets. Vice versa if it's not checked.
If a library uses this option there should be no need to calculate and maintain the 'pages' cache or interpret a spine width template.
BR