Select large groups of messages in one click

The ability, in select mode, to select "from current message to beginning of chat" (or end) would allow the user to alleviate the context window by excluding the beginning of the conversation while still keeping the latest portion of previous messages. Even better would be the equivalent of “shift + select” to select a range of messages in one click.
It is doable right now, but only by clicking on each message one by one.