Implemented and fixed many issues

Client/streamhub-qt/PlotWidget.h

@@ -21,6 +21,7 @@
 class QHBoxLayout;
 class QToolButton;
 class QLabel;
+class QMenu;
 
 namespace shq {
 
@@ -69,6 +70,8 @@ private:
     friend class PlotCanvas;
 
     void rebuildHeader();
+    void buildVScaleMenu(QMenu* vs, VScale& evs);
+    void showUnifiedVScaleMenu(const QPoint& globalPos);
     void showBadgeMenu(int slotIdx, const QPoint& globalPos);
     void pushZoomHist();
     void initPlotX(double tMax);
@@ -87,7 +90,8 @@ private:
     bool   paused_     = false;
     double plotXMin_   = 0.0;
     double plotXMax_   = 0.0;
-    int    vMode_      = 0;     /* 0 normal 1 digital 2 mixed */
+    int    vMode_      = 0;     /* 0 normal 1 digital 2 mixed 3 unified */
+    VScale uniVS_;              /* the one scale every trace shares in mode 3 */
     int    activeSlot_ = -1;
     bool   trigZoomed_ = false;