GUI: run per-chan osc on instrument preview

src/engine/engine.cpp

@@ -1743,6 +1743,10 @@ bool DivEngine::isPlaying() {
   return (playing && !freelance);
 }
 
+bool DivEngine::isRunning() {
+  return playing;
+}
+
 bool DivEngine::isStepping() {
   return !(stepPlay==0);
 }

src/engine/engine.h

@@ -654,6 +654,9 @@ class DivEngine {
 
     // is playing
     bool isPlaying();
+    
+    // is running
+    bool isRunning();
 
     // is stepping
     bool isStepping();

src/gui/chanOsc.cpp

@@ -312,7 +312,7 @@ void FurnaceGUI::drawChanOsc() {
           inRect.Max.y-=dpiScale;
           ImGui::ItemSize(size,style.FramePadding.y);
           if (ImGui::ItemAdd(rect,ImGui::GetID("chOscDisplay"))) {
-            if (!e->isPlaying()) {
+            if (!e->isRunning()) {
               for (unsigned short i=0; i<512; i++) {
                 float x=(float)i/512.0f;
                 waveform[i]=ImLerp(inRect.Min,inRect.Max,ImVec2(x,0.5f));