try to fix some weird focus issues

src/fluxbox.cc

@@ -825,6 +825,7 @@ void Fluxbox::handleEvent(XEvent * const e) {
         // a grab is something of a pseudo-focus event, so we ignore
         // them, here we ignore some window receiving it
         if (e->xfocus.mode == NotifyGrab ||
+            e->xfocus.mode == NotifyUngrab ||
             e->xfocus.detail == NotifyPointer ||
             e->xfocus.detail == NotifyInferior)
             break;