GNOME Bugzilla – Bug 787846
When mouse profile is set to Flat, the slider for Mouse Speed allows you to essentially disable your mouse.
Last modified: 2017-09-18 17:34:49 UTC
I use the GNOME Tweak Tool to change my mouse profile from Default (acceleration is used) to Flat (acceleration is not used). After doing this, if I adjust the Mouse Speed under Settings for Mouse & Touchpad to the farthest left, my mouse is effectively disabled as I believe this is setting the DPI used to 0, since it isn't adjusting mouse acceleration anymore. I also want to point out that this setting is updated immediately, even though Settings has a "Test Settings" button. Meaning, if you adjust the slider to the farthest left to see what the lowest value is, it takes effect immediately with no easy way to undo the setting change.
*** This bug has been marked as a duplicate of bug 784451 ***