Add a `nav_get(target)` function to obtain the currenly selected nav_panel of a target nav container

[ariebh]

It's currently possible to select, insert, remove, show or hide a nav panel of a parent container, but it isn't possible to query what panel is currently selected.

This feature would be useful for programmatically updating page contents based on the query result.

[cpsievert]

It isn't possible to query what panel is currently selected.

Are you aware that by adding an id (to the navset_() container) you can read the selected panel via an input value?

library(shiny)
library(bslib)

ui <- page_fluid(
  navset_card_tab(
    id = "tabs",
    nav_panel("A", "a"),
    nav_panel("B", "b")
  )
)

server <- function(input, output, session) {
  observe(print(input$tabs))
}

shinyApp(ui, server)