When X and Y axis are enabled to show slider - please change mouse wheel behavior to ONLY allow zoom-in/out on X axis. Y axis gets custom zoom level set by the sliders, leave it untouched. This will preserve behavior that is common practice across many other platforms.
Also, when Trellis is enabled with panel view, + X-axis is enabled with zoom slider, please give priority for X-axis zoomin from mouse wheel. Let user know that PgUP / PgDown can be used to navigate between trellis panels.