test

mon = peripheral.find("monitor")
mX, mY = mon.getSize()
activeScreen = 1

function monPrint(txt)
 local this = term.current()
 term.redirect(mon)
 print(txt)
 term.redirect(this)
end

function drawActiveScreen()
 if screens[activeScreen] then
  setlabel(screens[activeScreen]())
 else
  print("something went wrong!")
 end
end

function setlabel(text)
 mon.setBackgroundColor(colors.gray)
 mon.setTextColor(colors.white)
 for i=1,3 do
  mon.setCursorPos(1,mY-i-3)
  mon.write("                                                                                                          ")
 end
 cWrite(text,mY-5)
end

function screen1()
 mon.setCursorPos(1,1)
 mon.setBackgroundColor(colors.black)
 mon.setTextColor(colors.yellow)
 mon.write("Main information:")
 mon.setCursorPos(1,3)
 mon.setTextColor(colors.white)
 monPrint("You can rightclick the buttons below to switch tabs to see more info on ranks, paths and their differences.")
 return "  Information"
end

function screen2()
 mon.setCursorPos(1,1)
 mon.setBackgroundColor(colors.black)
 mon.setTextColor(colors.yellow)
 mon.write("Rank type 1 information:")
 mon.setTextColor(colors.white)
 mon.setCursorPos(1,3)
 monPrint("These ranks blablabla information blabla sigh I gotta sleep")
 return "Rank type 1"
end

function screen3()

 return "Rank type 2"
end

function cWrite(text,line)
 local len = string.len(text)
 mon.setCursorPos(math.ceil(mX/2)-(len/2),line)
 mon.write(text)
end

function drawButton(mode,active)
 local text = "unset"
 if active == true then
  mon.setBackgroundColor(colors.white)
 else
  mon.setBackgroundColor(colors.lightGray)
 end
 mon.setTextColor(colors.black)
 if mode == "prev" then
  xStart = 1
  text = "Back"
 else
  xStart = (mX-1)/2 + 2
  text = "Next"
 end
 bgText = ""
 repeat
  bgText = bgText.." "
 until string.len(bgText) >= math.floor(mX/2)
 for i=1,3 do
  mon.setCursorPos(xStart,mY-(i-1))
  mon.write(bgText)
 end
 if mode == "prev" then
  mon.setCursorPos(xStart+5,mY-1)
 else
  mon.setCursorPos(xStart+5,mY-1)
 end
 mon.write(text)
end

function main()
 mon.setBackgroundColor(colors.black)
 mon.clear()
 drawButton("prev")
 drawButton("next")
 drawActiveScreen()
 event = {os.pullEvent("monitor_touch")}
 centerP = mX / 2
 --print(textutils.serialize(event))
 if event[4] >= mY-3 then
  if event[3] < centerP then
   activeScreen = activeScreen - 1
   if activeScreen == 0 then
    activeScreen = #screens
   end
  elseif event[3] > centerP then
   activeScreen = activeScreen + 1
   if activeScreen > #screens then
    activeScreen = 1
   end
  end
 end
 --print(activeScreen)
end

screens = {screen1,screen2,screen3}
while true do
 main()
end