Shinydashboard 'topbar'

Hi You can do something like this:

library(shiny)
library(shinydashboard)

CustomHeader <- dashboardHeader()
CustomHeader$children[[3]]$children <-  div(style="min-width:200px;",tags$input(id="searchbox",placeholder = "  Search...",type="text",class="chooser-input-search",style="width:200px;height:50px;"))

ui <- dashboardPage(
  CustomHeader,
  dashboardSidebar(),
  dashboardBody()
)
server <- function(input, output, session) {}
shinyApp(ui, server)

Based on Pork Chop answer, you can simply use selectInput (or other shiny inputs) that you put in a div with float:left to span horizontally:

CustomHeader <- dashboardHeader()
CustomHeader$children[[3]]$children <- list(
  div(style="float:left;height:50px",selectInput("select1", NULL, c("a","b","c"))),
  div(style="float:left;height:50px",selectInput("select2", NULL, c("d","e","f"))))

ui <- dashboardPage(
  CustomHeader,
  dashboardSidebar(),
  dashboardBody(textOutput("text1"),textOutput("text2"))
)

server <- function(input, output, session) {
  output$text1 <- renderText({input$select1})
  output$text2 <- renderText({input$select2})
}

shinyApp(ui, server)