Canceling mousemove will not prevent text selection or drag-and-drop. Chrome allowed canceling mousemove events to prevent other APIs like text selection (and even drag-and-drop in the past). This does not match other major browsers; nor does it conform to the UI Event spec: https://w3c.github.io/uievents/#event-type-mousemove Through this feature, text selection will no longer be the default-action of mousemove. Text selection and drag-and-drop can still be prevented through canceling selectstart and dragstart events respectively, which are spec compliant and fully interoperable.