title: eventReactive with 2 action button across 2 tabs
body: <p>I have an app with 2 tabs, each has an action button. I want the same process to be triggered if either buttons is pressed. So I wrote it the following way:</p>
  
  <pre><code>library(shiny)
  
  ui &lt;- fluidPage(
    tabsetPanel(
      tabPanel("tab1",
        actionButton("btn1","Button 1"),
        textOutput("text")
      ),
      tabPanel("tab2",
        actionButton("btn2","Button 2")
      )
    )
  
  )
  
  server &lt;- function(input, output) {
    data=eventReactive(c(input$btn1,input$btn2),{
      print("Button is pressed!")
      print(input$btn1)
      print(input$btn2)
      iris
    })
    output$text=renderText({
      req(data())
      print(head(data()))
      "Really? Button is pressed!"
    })
  }
  
  # Run the application 
  shinyApp(ui = ui, server = server)
  </code></pre>
  
  <p>And I don't understand why the <code>eventReactive</code> expression is triggered when the app initialize, before any button is pressed.</p>
  
  <p>If I only work with 1 button, i.e. <code>input$btn1</code> instead of <code>c(input$btn1, input$btn2)</code> then I get the expected behaviour, but not with 2 dependencies.</p>
  
  <p>Can someone enlighten me?</p>