hide invite button when peer trust us.

Change-Id: Ie656c6b96057d22d2a1da1d68425b93a1be8050a
Tuleap: #1628
diff --git a/src/chatview.cpp b/src/chatview.cpp
index 4ab82f0..3aab250 100644
--- a/src/chatview.cpp
+++ b/src/chatview.cpp
@@ -525,6 +525,9 @@
         }
 
         gtk_combo_box_set_active(GTK_COMBO_BOX(priv->combobox_cm), last_used_cm_idx);
+
+        if (last_used_cm->isConfirmed())
+            gtk_widget_hide(priv->button_send_invitation);
     }
 
     /* if there is only one CM, make the combo box insensitive */