title: Backspace key deletes following character, not preceding character
body: <p>first of all, sorry for my poor english..</p>
  
  <p>I have installed emacs on linux mint, and i have set up my own config. 
  Everything is all right except that the key backward delete the char on the right, (however it is supposed to delete the left one).
  how can i change this key comportement ? 
  i have try to code with it, but its so hard to change the way i'm coding.
  I have look on the internet but didn't find anwser to this specific problem.</p>
  
  <p>my backward key act like a the delete key ( and i'm working on mac air so i don't have the del key wich may cause the problem ? ) </p>
  
  <p>thanks. </p>