ortho      = frame.viewPanels[0]
profile    = ortho.getCurrentProfile()
displayCtx = ortho.displayCtx

def onmouse(ev, canvas, mousePos, canvasPos):
    overlay  = displayCtx.getSelectedOverlay()
    opts     = displayCtx.getOpts(overlay)
    worldLoc = displayCtx.location
    voxelLoc = opts.getVoxel(worldLoc)
    print('Location changed: {}'.format(voxelLoc))
    print(canvasPos)

profile.registerHandler('LeftMouseDown', 'mylistenername', onmouse)

As of FSLeyes 0.20.0, it is no longer necessary to create a `Profile` sub-class in order to be notified of mouse/keyboard events. Instead, you can use the `Profile.registerHandler` method like so: ```python ortho = frame.viewPanels[0] profile = ortho.getCurrentProfile() displayCtx = ortho.displayCtx def onmouse(ev, canvas, mousePos, canvasPos): overlay = displayCtx.getSelectedOverlay() opts = displayCtx.getOpts(overlay) worldLoc = displayCtx.location voxelLoc = opts.getVoxel(worldLoc) print('Location changed: {}'.format(voxelLoc)) print(canvasPos) profile.registerHandler('LeftMouseDown', 'mylistenername', onmouse) ```