To go all the way to a "Stop" requires using the Velocity Envelope. I believe that may only be available in the Pro version.
As was mentioned, you can hold down the CTRL key and resize the event LONGER which will slow it down - you can go down to 25% of the original speed. that way. If you right-click the event and choose properties, look at the "Playback Rate". Holding down CTRL and resizing actually just changes that value.
If you don't have pro (don't have velocity envelope) and you want to slow it down even further. Use the control;drag to the max, then render the scene to another track and do it again.