Disable shiftclick on TimePowerSquareWidget

sohstationviewer/view/plotting/plotting_widget/plotting_widget.py

@@ -309,15 +309,22 @@ class PlottingWidget(QtWidgets.QScrollArea):
         When click mouse on the current plottingWidget, SOHView will loop
             through different plottingWidgets to do the same task for
             interaction:
-            + shift+click: call on_shift_click() to do zooming
+            + shift+click: call on_shift_click() to do zooming. This is
+                disregarded in TimePowerSquareWidget because it isn't subjected
+                to be zoomed in.
             + ctrl+click or cmd+click in mac: call on_ctrl_cmd_click() to show
                 ruler
 
         :param event: button_press_event - mouse click event
         """
         modifiers = event.guiEvent.modifiers()
+        if (modifiers == QtCore.Qt.ShiftModifier and
+                self.name == "timepowersquaredwidget"):
+            # not start zooming from TimePowerSquareWidget
+            return
+
         try:
-            # on_pick() take place after on_pick_on_artist where
+            # on_button_press_event() take place after on_pick_event where
             # tps_t was assigned in TimePowerSquareWidget
             xdata = self.tps_t
         except AttributeError: