   hook 'mousedown', 6, (point, event, state) ->
     # If someone else has already taken this click, pass.
     if state.consumedHitTest then return
+
+    # If it's not a left-click, pass.
+    if event.which isnt 1 then return
 
     palettePoint = @trackerPointToPalette point
     if @scrollOffsets.palette.y < palettePoint.y < @scrollOffsets.palette.y + @paletteCanvas.height and

    # If someone else has already taken this click, pass.
    if state.consumedHitTest then return

    # Hit test against the tree.
    mainPoint = @trackerPointToMain(point)
    hitTestResult = @hitTest mainPoint, @tree

    unless state.clickedLassoSegment then @clearLassoSelection()

    if state.consumedHitTest or state.suppressLassoSelect then return

    # If it's not a left-click, pass.
    if event.which isnt 1 then return

    # If the point was actually in the main canvas,
    # start a lasso select.
