show system elements when first staff is hidden

Author: wschweer

libmscore/measure.cpp

@@ -2426,7 +2426,7 @@ void Measure::scanElements(void* data, void (*func)(void*, Element*), bool all)
                   e->scanElements(data, func, all);
                   }
             foreach(Element* e, s->annotations()) {
-                  if (all || visible(e->staffIdx()))
+                  if (all || e->systemFlag() || visible(e->staffIdx()))
                         e->scanElements(data,  func, all);
                   }
             }

libmscore/system.cpp

@@ -350,6 +350,8 @@ void System::layout2()
             if (firstStaffIdx == -1)
                   firstStaffIdx = staffIdx;
             }
+      if (firstStaffIdx == -1)
+            firstStaffIdx = 0;
 
       qreal systemHeight = staff(lastStaffIdx)->bbox().bottom();
       setHeight(systemHeight);

mscore/seq.cpp

@@ -1250,6 +1250,10 @@ void Seq::putEvent(const Event& event)
       if (!cs)
             return;
       int channel = event.channel();
+      if (channel >= cs->midiMapping()->size()) {
+            qDebug("bad channel value");
+            return;
+            }
       int syntiIdx= cs->midiMapping(channel)->articulation->synti;
       synti->play(event, syntiIdx);
       }