So, I've been working on a project that involves having moveable lines on my plot in Shiny. I've followed the answers given here and it worked really great! Then, I needed to make some modifications which happened here. So far, so good. However, my issue now is that I am trying to add a second moveable line onto this plot, and it's really not working out. Every time I move the second line, the first one reverts back to its original position. I have a feeling this is because !is.null(d[["shape[0].x0"]]) is evaluating to be FALSE, making the line go back to the minimum x value. Perhaps I've done something wrong here, especially since I'm quite new with Shiny. You can see a GIF attached which demonstrates the issue:

Here is my code, with the data modified so that it can be reproduced.

I think my issue is in the selected_point variable. I am trying to create two points, (x,y) and (x2,y2) so that I can "save" both intersections of the vertical lines with the curve in red. However, I feel like I am doing something wrong here. The problem could also be in the plot_ly function and how I am implementing the vertical lines, but I'm really not sure. Any help, hints, or tips would be much appreciated!

```
server <- function(input, output, session) {
rv <- reactiveValues(x = NULL, y = NULL, x2 = NULL, y2 = NULL)
s <- reactive({
rv$x <- c(-100:100)
rv$y <- c(-100:100)**2
rv$x2 <- c(-100:100)
rv$y2 <- c(-100:100)**2
d <- event_data("plotly_relayout", source = "trajectory")
selected_point <- if (!is.null(d[["shapes[0].x0"]])) {
xint <- d[["shapes[0].x0"]]
xpt <- rv$x[which.min(abs(rv$x - xint))]
rv$save_x <- xpt
if (!is.null(d[["shapes[1].x0"]])) {
xint2 <- d[["shapes[1].x0"]]
xpt2 <- rv$x[which.min(abs(rv$x - xint2))]
rv$save_x2 <- xpt2
list(x = xpt, y = rv$y[which.min(abs(rv$x - xint))],
x2 = xpt2, y2 = rv$y[which.min(abs(rv$x - xint2))])
}
else {
list(x = xpt, y = rv$y[which.min(abs(rv$x - xint))],
x2 = min(rv$x), y2 = rv$y[which(rv$x == min(rv$x))])
}
} else {
if (!is.null(d[["shapes[1].x0"]])) {
xint2 <- d[["shapes[1].x0"]]
xpt2 <- rv$x[which.min(abs(rv$x - xint2))]
rv$save_x2 <- xpt2
list(x = min(rv$x), y = rv$y[which(rv$x == min(rv$x))],
x2 = xpt2, y2 = rv$y[which.min(abs(rv$x - xint2))])
}
else{
list(x = min(rv$x), y = rv$y[which(rv$x == min(rv$x))],
x2 = min(rv$x), y2 = rv$y[which(rv$x == min(rv$x))])
}
}
plot_ly(color = I("red"), source = "trajectory") %>%
add_lines(x = rv$x, y = rv$y) %>%
add_markers(x = selected_point$x, y = selected_point$y) %>%
add_markers(x = selected_point$x2, y = selected_point$y2) %>%
layout(shapes = list(
list(
type = "line",
line = list(color = "gray", dash = "dot"),
x0 = selected_point$x,
x1 = selected_point$x,
y0 = 0,
y1 = 1,
yref = "paper"),
list(
type = "line",
line = list(color = "black", dash = "solid"),
x0 = selected_point$x2,
x1 = selected_point$x2,
y0 = 0,
y1 = 1,
yref = "paper")
)) %>%
config(editable = TRUE)
})
output$new_plot <- renderPlotly({
s()
})
})
ui <- fluidPage(
plotlyOutput("new_plot")
)
```