title: How can I make scrollable gamefield in Lazarus?
body: <p>I would like make a small RTS game in Lazarus and therefore I would like make a scrollable gamefield with arrow keys in it.
  Now I created a bigger TBitmap (a big blue image) on the smaller TForm1 and I draw the game elements on this TBitmap. Although I can move this TBitmap and the elements on it with the arrow keys, but I can't delete the moving units from the previous place.
  Maybe the canvas of a TBitmap is can't be deleted? But in this case how can I make a scrollable gamefield?
  <img src="https://i.stack.imgur.com/0WRSK.jpg" alt="Game field with moving unit" /></p>