Prevent saving duplicate books

[oderyn]

When searching for a book, indicate whether a book has already been saved.

[oderyn]

Same UI as shown in #30

When you click save, turn the "Save" button into an "Edit" button. Likewise, if the page loads and a book is being displayed that has already been saved, display the "Edit" button. Like so:

[wolflu05]

Just discovered this software and starting to really liking it because its lightweigt, but I have the same problem. Would be really cool to have this fixed.

[wars2k]

Thanks for the comment @wolflu05 , I'll add this to my list to include in the next version.