How can I select one byte at a time?

I'm looking at a capture of a HTTP packet. If I let my mouse cursor hover the hex dump in the packet bytes panel, entire sections of bytes are selected or highlighted at the same time. For example, if I put my mouse cursor over the section belonging to a single HTTP header, the entire header is highlighted.

How do I turn this behaviour off? I would like to only highlight a single byte at a time, as this is much more useful for debugging non-ASCII encodings.