In list view in the Finder in Panther, the whole line is highlighted to note that the item it selected. But in all previous version of the OS, and in most of Panther, you can drag what is highlighted. But in list view, despite the whole line being highlighted, you can only drag the text and icon, not any part of the highlighted section.
Now, there is a small border around the text and icon that you can also drag, but it is impossible to tell where that border ends, because the highlighting doesn't end at the border, like it clearly should. This is related to the other highlighting problems, such as that something that has a blue label in list view is only barely distinguishable from one that is selected (given a blie highlight color). And if you select the item with a blue label, the label disappears, and you get instead a blue dot next to the name.
It's really exceptionally poor design, how labels and highlighting are done in Panther.