1. Clicking the file checkboxes shouldn't "select" the files for the Properties panel, IMO.
When you want to view a file's properties, you properly select it: That should be the expected behavior.
Clicking the checkboxes should only affect the item's checked state.
Otherwise, when the app is forced to parse each item's properties, it can be excruciating to try and "quickly" select which items are enabled while you have to wait for the parsing to finish.
2. Even when several files are selected, pressing space only toggles the immediately focused item.
This makes enabling/disabling multiple items impossible, which is especially bad with point 1 being an issue.
All selected items should be toggled.
Here's a video showcasing the issue.
https://youtu.be/NlHrfTgnKEQ