My buffer slips to the right while editing a file. Whenever I press a button, left margin area grows one character. This isn't happening for all files. My buffer normally looks like this:
line with text
another line with text
After I push a buttons, the screen slips to the right, left margin area grows and the buffer looks like this:
<this area got wider> line with text
<this area got wider> another line with text
This problem did not occur for all files; but it isn't resolved with restarting the Emacs.