Library "Upgrade Spell" applies to the last spell you moused over, not the spell you selected

darkpck

Steps to reproduce:

1. Click a spell
2. Move the cursor to the Upgrade spell button, navigating over another spell
3. The sub-window now displays the last spell that was moused over, not the selected spell

Here is a screenshot: https://i.imgur.com/NhrYc8a.png

You can see that I selected Saproling Swarm (it's surrounded by the box), then went to upgrade it, but because Elven Assailment gets moused over, the spell that gets upgraded is Elven Assailment. This is exacerbated by the placement of the "Upgrade Spell" button which means you have to go over other spells unless you take a circuitous route around the UI with the cursor.

Now I spent 6000 spell pages for Elven Assailment when I was waiting to upgrade Forest to 8, despite the fact that I clicked a completely different spell. That's 6000 spell pages wasted. It's obvious that if you select something that you want to upgrade, it should upgrade that item, not something unrelated that you moused over.

Please address this terrible design.