Change torrent delete behavior when multiple categories are selected

[chincotaco]

When I manually delete torrents, I generally click on the top one and use shift + down arrow to select more. This morning I did just this, but accidentally selected a category. Because the highlight for the category is much more subtle than the highlight for the torrents themselves, I didn't notice, confirmed the delete, and lost *every* torrent in that category.

Maybe you should add a dialog box, or simply make it so that deleting a category header itself doesn't do anything.

[livings124]

There is an option (enabled by default) to show a warning when you delete transfers from the list, and it is enabled by default. The dialog also gives context on the number of torrents to be deleted.