[gtk+] Clarify docs a bit

[Matthias Clasen <matthiasc src gnome org>]

commit 101cecf7248f7b1ff7d1f66c782a26832a392dbb
Author: Matthias Clasen <mclasen redhat com>
Date:   Fri Apr 15 22:13:30 2016 -0400

    Clarify docs a bit
    
    The wording here was just awkward: TRUE is returned if... Note that
    FALSE is also returned if...

 gdk/gdkkeys.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/gdk/gdkkeys.c b/gdk/gdkkeys.c
index d9185fd..d7f76a9 100644
--- a/gdk/gdkkeys.c
+++ b/gdk/gdkkeys.c
@@ -613,7 +613,7 @@ gdk_keymap_add_virtual_modifiers (GdkKeymap       *keymap,
  * This function is useful when matching key events against
  * accelerators.
  *
- * Returns: %TRUE if no virtual modifiers were mapped to the
+ * Returns: %FALSE if two virtual modifiers were mapped to the
  *     same non-virtual modifier. Note that %FALSE is also returned
  *     if a virtual modifier is mapped to a non-virtual modifier that
  *     was already set in @state.