I am trying to combine plotly interactivity with shiny:

plot_ly(data = iris, x = ~Sepal.Length, y = ~Petal.Length)

by brushing with constant mouse movement, the selection is correct with x and y axis like this:

However, if user hand moved up or down, the selection box will get compromised ending in undesirable selection.

I want to force the first way of selection (everything along x-axis).

Any help is appreciated.