This generates an object representing click options, to be passed as the
click argument of imageOutput or
plotOutput.
clickOpts(id = NULL, clip = TRUE)Input value name. For example, if the value is "plot_click",
then the click coordinates will be available as input$plot_click.
Should the click area be clipped to the plotting area? If FALSE, then the server will receive click events even when the mouse is outside the plotting area, as long as it is still inside the image.