The SWS / S&M extension is a collection of features that seamlessly integrate into REAPER, the Digital Audio Workstation (DAW) software by Cockos, Inc.
It is a collaborative and open source project.

SWS/S&M Extension

Zoom + Scroll

This category of actions allows simple, one key zoom in and out, as well as other zoom features, depending on the actions you pick. 
Bind one of the following to a convienient key!

Action List

Drag zoom (à la Wavelab/Cubase)

This feature allows you to zoom in the arrange view by grabing the timeline (top ruler) with the left mouse button and drag down/up to zoom in/out.
Note: this feature is disabled by default.

Zoom preferences

To enable and/or tweak zoom features: Main menu > Extension > Zoom preferences...