[apps][escher] Add methods 'handleEventWithText' in TextField and

TextArea to fix bug in probability (adding a toolbox text from the
calculations controller)

apps/shared/text_field_delegate_app.cpp

@@ -102,9 +102,7 @@ bool TextFieldDelegateApp::textFieldDidReceiveEvent(TextField * textField, Ion::
       textField->setEditing(true);
     }
     const char * xnt = privateXNT(textField);
-    textField->insertTextAtLocation(xnt, textField->cursorLocation());
-    textField->setCursorLocation(textField->cursorLocation()+strlen(xnt));
-    return true;
+    return textField->handleEventWithText(xnt);
   }
   return false;
 }