French accents on Yosemite
From Apple KB - OS X Yosemite: Enter characters with accent marks


  
  Press and hold a key on the keyboard (for example, e) to display an accent menu.
  
  If the key you press and hold doesn’t have any possible accent marks, the menu isn’t shown.
  Select a character (for example, é).
  
  Click a character, press the number key shown for a character, or use the arrow keys to cycle through the characters. Then press the Space bar to select one.
  
  
  You can also enter characters with accent marks using the Keyboard Viewer or Character Viewer.
  
  Use the Keyboard Viewer
  Use the Character Viewer
  Use input sources to type in other languages
  Format text in documents  


The press &amp; hold accent menu can be enabled or disabled from Terminal

To disable the character accent menu in OS X, launch Terminal from /Applications/Utilities, enter the following command and press Return:

defaults write -g ApplePressAndHoldEnabled -bool false

To re-enable, change false to true