title: R Shiny horizontal section
body: <p>I have the graphic of the evolution of a firm`s Assets and I want to draw a horizontal section hat is parallel with the Ox axis from 300000 to 400000, that should indicate the optimal value of this indicator(what the stakeholders want) and the line(the graphic itself) should be over that section to see immediately if the value at a certain time is good or not.</p>
  
  <pre><code>#date_a
  An         AI       AC    AT
  2011    147198  292282  439480
  2012    164660  175440  340100
  2013    153755  202013  355768
  2014    141857  242317  384174
  2015    137748  270366  408114
  2016    129087  397289  526376
  
  #in ui.r
  fluidRow(
                    width="100%",
                    column(4,plotOutput(outputId = "act", height = 100))
                  ),
  #in server.r
    output$act&lt;- renderPlot({
      ggplot(date_a, aes(date_a$An, date_a$AT)) + 
        geom_line(aes(group=1), colour="#000000") +
        geom_point(size=3, colour="#FF0000")+
        labs(x = "An", y = "Active(lei)") +
        ggtitle("Evolutia activelor totale")
    })
  </code></pre>