Two thoughts

First it would be nice to have an ongoing total of the cost of spells added the spellbook at the bottom of the selected spells list.

Second I see it previously mentioned by Moonglow but didn't see a response to the fact that card images persist if another card is selected and need to be actively deselected to be closed.  Being able to close the image by clicking on it somewhere or simply having it disappear when another card is selected would be nice. 

useful tool.