How to add a Session Box

This clip is taken from a longer Control Surface Studio walkthrough video
🎥 Watch the full CSS walkthrough video

In Control Surface Studio, a session box (commonly referred to as a red box) lets you visually see and control a specific section of Ableton Live’s Session View using your MIDI controller.

This guide explains how to add and configure your own custom session box, along with clip launch buttons and LED feedback.

What Is a Session Box?

A session box defines which tracks and scenes your MIDI controller can control at any time. With CSS, you can:

  • Create a custom-sized session box.
  • Add mappings like clip launch, mixer, and device controls that follow the session box position.
  • Synchronize multiple session boxes across different scripts using Combination Mode.

Add a Session Box Mapping

  1. Open the Mapping Type menu, select Session Box.
  2. The Session Box settings menu will display.

Configure the Session Box Position and Size

  • Offset Position from Left: Determines how many tracks from the left the session box is initially positioned at.
  • Offset Position from Top: Determines how many scenes from the top the session box is initially positioned at.
  • Combination Mode: Turn this on if you want the session box position to link with other session boxes in different CSS scripts (Combination Mode must be enabled in all scripts).
  • Width: Number of tracks (columns) the session box spans.
  • Height: Number of scenes (rows) it covers.

Example: Set Width to 4 and Height to 1 for a 4-track wide, 1-scene tall session box.
The preview red box in the settings menu updates to reflect these values.

Add optional Session Box controls

You can also assign the following (optional) buttons:

  • Clip Launch
  • Stop Track
  • Scene Launch
  • Stop All Clips

These are useful for expanded control but can be left unassigned if not needed.

Configure LED Feedback for Clip States

Below the button assignments, configure LED values for different clip states. Examples:

  • Clip Started → 127
  • Clip Stopped → 0
  • Clip Trigger to Play → 75

Final Steps

  1. Click Save to confirm the session box mapping.
  2. Save the overall script.
  3. Click Generate into Ableton Live.
  4. Reload the MIDI Remote Script in Ableton Live.

This setup gives you full clip-launch control with visual LED feedback from your MIDI controller.

Next you could add controls to move the session box around your Ableton session.
To do this, see our article on how to add Session Box Navigation.