When a payee is related to a category (wich is very handy), you cannot delete this category any more : you must first change the payee(s) preferences.

Now if you have a lot of payees and a bunch of categories to delete, this can take some time to fix one by one.

It would be very pleasant to change all related payees to another categorie on a single right click ! Or at least to have a list of all payees related to this category.

Reproducible: Always

Steps to Reproduce:
1.attribute a category to a payee
2.try to erase the category
3.

Actual Results:  
Impossible to erase AND no message tells you why.

Expected Results:  
1. a message explaining what to do
2. a list of all payees related to the category
3. the ability to change all payees to another category