I see davidfor isn't letting me forget either
. I'm starting to take a look at it now, I think I will push it out before I start my other major work with this plugin.
I'm going to completely remove the existing "Move" menus, that are only enabled if you were viewing a list. Instead there will be a new "Move to list..." menu option, which is always going to give you a new popup dialog.
As mentioned previously, there are various complications to be handled, such as the selected books not being currently on any lists or indeed being on multiple lists that might not be in common. I think the most "user friendly" way of handling all this is basically not caring about it
. In other words, you will always get shown the dialog, regardless of what lists the selected books might be on.
As said previously the left side of the dialog will be a choice of zero, one or many list(s) to remove books from, and the right side a choice of a single list to add books to. Any lists you choose on the left hand side of the dialog, all books will be attempted to be removed from. If you select no lists (or the books weren't on any so you have no choices), then the whole operation gets treated the same as doing an Add.
Makes sense in my head anyways...