Kensington SlimBlade on Linux: Custom Button Mapping & Left-Handed Setup

The Kensington SlimBlade and SlimBlade Pro are legendary among trackball enthusiasts for their massive 55mm ball and unique twist-to-scroll mechanism. However, because they are symmetrical (ambidextrous), the default click behavior might not match your workflow, especially if you want to use the device with your left hand.

On Linux X11, you do not need bloated software to change how your trackball behaves. Using xinput and a simple config file, you can swap clicks, remap back/forward buttons, and create a perfectly ergonomic setup.

Why remap your SlimBlade?

The SlimBlade features four large buttons surrounding the ball. By default, Linux treats these in a standard way, but many users prefer:

• Left-handed use: Swapping the primary and secondary click buttons so your thumb handles the main action.
• Improved navigation: Moving "Back" and "Forward" to the top buttons for easier access.
• Accidental click prevention: Disabling specific button zones that you frequently hit accidentally.

Step 1: Identify your device

First, find out how Linux sees your trackball. Open your terminal and run:

xinput list

Look for a line containing "Kensington SlimBlade". Note the name or the ID number. Then, view the current default mapping:

xinput get-button-map <device-id>

You will likely see a sequence like 1 2 3 4 5 6 7 8 9. Each position in this list represents a physical button action.

Step 2: Test a new mapping live

To swap your left and right clicks (useful for left-handed setups) and adjust navigation buttons, you can use the following proven mapping:

xinput set-button-map <device-id> 3 8 1 0 5 0 9 4 9

What this specific map does:

• Swaps the primary click buttons (Left becomes Right, Right becomes Left).
• Positions the "Back" and "Forward" actions on the upper buttons.
• Cleans up unused button assignments to prevent "ghost" clicks.

Test the device immediately. If the clicks feel reversed or the navigation is wrong, you can revert to the default by running xinput set-button-map <device-id> 1 2 3 4 5 6 7 8 9.

Step 3: Make it permanent

The xinput command only lasts until you log out. To make your custom layout stick after every reboot, you need to create an X11 configuration rule.

Create the following file (you will need sudo/root privileges):

/etc/X11/xorg.conf.d/99-kensington-trackball.conf

Add this content:

Section "InputClass"
    Identifier "Kensington SlimBlade"
    MatchProduct "Kensington SlimBlade"
    Driver "libinput"
    Option "ButtonMapping" "3 8 1 0 5 0 9 4 9"
EndSection

Note: If your system uses the older evdev driver instead of libinput, ensure the Driver line matches your system configuration.

Tuning your own layout

If the mapping above is not quite right for your hand size or preference, you can find your own perfect map using the xinput test tool:

1. Run xinput test <device-id>.
2. Click each physical button on the SlimBlade.
3. Watch the terminal output to see which button number (1, 2, 3, etc.) is triggered.
4. Rearrange those numbers in your set-button-map command until the behavior matches your intent.

FAQ

Does this work for both the Wired and Pro (Wireless) versions?

Yes. Using the MatchProduct "Kensington SlimBlade" string in your config file is broad enough to catch both the classic wired model and the newer SlimBlade Pro.

How do I configure this on Wayland?

Wayland handles input remapping differently than X11. Instead of Xorg config files, you may need to use tools like input-remapper or compositor-specific settings (like those found in GNOME or KDE Plasma) to achieve the same result.

Can I remap the "Twist to Scroll" behavior?

The twist action is usually interpreted as a high-speed scroll wheel (buttons 4 and 5). While you can remap those numbers, it is generally recommended to keep them as-is to preserve the unique scrolling experience of the SlimBlade.

Final Thoughts

The beauty of using a high-end trackball on Linux is the level of granularity you have over your hardware. Whether you are remapping for left-handed use or just trying to optimize your muscle memory, these small changes remove significant friction from your daily workflow.

Just like optimizing your voice typing setup or finding the best Linux productivity tools, getting your physical inputs right is the first step toward a truly efficient workstation.