title: Corona - Lua - Dragging object without physics
body: <p>I am relatively new to coding in lua so bear with me. 
  I'm ultimately trying to setup a drag &amp; drop function for multiple 'tiles' on one scene. But to begin with (and to make sure I understand all of this correctly) I am just trying to get one tile moving around the screen. </p>
  
  <p>So I browsed the interwebs for a while and found the solution below (among other similar solutions) and implemented this myself with my own object names etc.</p>
  
  <p>It works great....but...unfortunatelt when i drag the object into the top right quadrant of the screen (on the simulator and a phone) the object gets stuck. It stops dragging as it hits any part of the top right quadrant of the screen, and I cannot re-select it to drag it back to the rest of the screen. </p>
  
  <p>Any ideas as to why this is happening?? (my code is below)</p>
  
  <pre><code>local _H = display.contentHeight
  local _W = display.contentWidth
  
  local notesGroup = display.newGroup()
  
  local tile1 = display.newImage ("graphics/image.PNG")
  tile1.x = _W/2
  tile1.y =  _H/2 
  
  function tile1:touch( event )
      if event.phase == "began" then
  
      self.markX = self.x    -- store x location of object
      self.markY = self.y    -- store y location of object
  
  elseif event.phase == "moved" then
  
      local x = (event.x - event.xStart) + self.markX
      local y = (event.y - event.yStart) + self.markY
  
      self.x, self.y = x, y   
  end
  
  return true
  </code></pre>
  
  <p>end</p>
  
  <pre><code>notesGroup:insert(tile1)
  
  tile1:addEventListener("touch", tile1)
  </code></pre>