docs: use proper apostrophe

https://wiki.gnome.org/Design/OS/Typography

gdk/x11/gdkcursor-x11.c

@@ -64,7 +64,7 @@ static guint theme_serial = 0;
 /* cursor_cache holds a cache of non-pixmap cursors to avoid expensive 
  * libXcursor searches, cursors are added to it but only removed when
  * their display is closed. We make the assumption that since there are 
- * a small number of display's and a small number of cursor's that this 
+ * a small number of display’s and a small number of cursor’s that this 
  * list will stay small enough not to be a problem.
  */
 static GSList* cursor_cache = NULL;

gdk/x11/gdkdisplay-x11.c

@@ -1981,9 +1981,9 @@ gdk_x11_lookup_xdisplay (Display *xdisplay)
 /**
  * _gdk_x11_display_screen_for_xrootwin:
  * @display: a #GdkDisplay
- * @xrootwin: window ID for one of of the screen's of the display.
+ * @xrootwin: window ID for one of of the screen’s of the display.
  * 
- * Given the root window ID of one of the screen's of a #GdkDisplay,
+ * Given the root window ID of one of the screen’s of a #GdkDisplay,
  * finds the screen.
  * 
  * Return value: (transfer none): the #GdkScreen corresponding to
@@ -2473,7 +2473,7 @@ gdk_x11_register_standard_event_type (GdkDisplay *display,
 }
 
 /* look up the extension name for a given major opcode.  grubs around in
- * xlib to do it since a) it's already cached there b) XQueryExtension
+ * xlib to do it since a) it’s already cached there b) XQueryExtension
  * emits protocol so we can't use it in an error handler.
  */
 static const char *
@@ -2788,8 +2788,8 @@ gdk_x11_display_error_trap_pop_ignored (GdkDisplay *display)
  * @sm_client_id: the client id assigned by the session manager when the
  *    connection was opened, or %NULL to remove the property.
  *
- * Sets the `SM_CLIENT_ID` property on the application's leader window so that
- * the window manager can save the application's state using the X11R6 ICCCM
+ * Sets the `SM_CLIENT_ID` property on the application’s leader window so that
+ * the window manager can save the application’s state using the X11R6 ICCCM
  * session management protocol.
  *
  * See the X Session Management Library documentation for more information on

gdk/x11/gdkkeys-x11.c

@@ -1042,7 +1042,7 @@ gdk_x11_keymap_lookup_key (GdkKeymap          *keymap,
  *  - add the group and level return.
  *  - change the interpretation of mods_rtrn as described
  *    in the docs for gdk_keymap_translate_keyboard_state()
- * It's unchanged for ease of diff against the Xlib sources; don't
+ * It’s unchanged for ease of diff against the Xlib sources; don't
  * reformat it.
  */
 static Bool
@@ -1444,7 +1444,7 @@ gdk_x11_keymap_add_virtual_modifiers (GdkKeymap       *keymap,
  * @keycode: the hardware keycode from a key event
  *
  * Determines whether a particular key code represents a key that
- * is a modifier. That is, it's a key that normally just affects
+ * is a modifier. That is, it’s a key that normally just affects
  * the keyboard state and the behavior of other keys rather than
  * producing a direct effect itself. This is only needed for code
  * processing raw X events, since #GdkEventKey directly includes

gdk/x11/gdkproperty-x11.c

@@ -383,11 +383,11 @@ _gdk_x11_get_xatom_for_display_printf (GdkDisplay    *display,
  * gdk_x11_get_xatom_by_name:
  * @atom_name: a string
  * 
- * Returns the X atom for GDK's default display corresponding to @atom_name.
+ * Returns the X atom for GDK’s default display corresponding to @atom_name.
  * This function caches the result, so if called repeatedly it is much
  * faster than XInternAtom(), which is a round trip to the server each time.
  * 
- * Return value: a X atom for GDK's default display.
+ * Return value: a X atom for GDK’s default display.
  **/
 Atom
 gdk_x11_get_xatom_by_name (const gchar *atom_name)
@@ -422,9 +422,9 @@ gdk_x11_get_xatom_name_for_display (GdkDisplay *display,
 
 /**
  * gdk_x11_get_xatom_name:
- * @xatom: an X atom for GDK's default display
+ * @xatom: an X atom for GDK’s default display
  * 
- * Returns the name of an X atom for GDK's default display. This
+ * Returns the name of an X atom for GDK’s default display. This
  * function is meant mainly for debugging, so for convenience, unlike
  * XAtomName() and gdk_atom_name(), the result 
  * doesn't need to be freed. Also, this function will never return %NULL, 

gdk/x11/gdkwindow-x11.c

@@ -5521,7 +5521,7 @@ gdk_x11_get_server_time (GdkWindow *window)
  * 
  * Returns the X resource (window) belonging to a #GdkWindow.
  * 
- * Return value: the ID of @drawable's X resource.
+ * Return value: the ID of @drawable’s X resource.
  **/
 XID
 gdk_x11_window_get_xid (GdkWindow *window)