Ctrl+LeftClick on any entity with inventory and on some entities without inventory "deletes" the cursor stack if the cursor stack has the "only-in-cursor" flag.
Expected Bahavior
"only-in-cursor" items can not be inserted into anything, so they should never be affected by "insert" actions.
Reproduction
Rocks are just an example. I also confirmed it on electric-energy-interface, rail, electric-pole, ... and then i stopped testing.
- Press Ctrl+C to get a copy-paste tool.
- Walk up to a rock and press Ctrl+LeftClick.
- Notice how your cursor is now empty.