Merge branch 'i275_error_clicking_on_outside_plot_area' into 'develop'

reset tps_t after using to prevent bug when clicking on no point area

Closes #275

See merge request !316

sohstationviewer/view/plotting/plotting_widget/plotting_widget.py

@@ -504,6 +504,9 @@ class PlottingWidget(QtWidgets.QScrollArea):
             if self.tps_t is None:
                 return
             xdata = self.tps_t
+            # Reset tps_t here because the reset in on_pick_event won't be
+            # reach when no point is clicked.
+            self.tps_t = None
         else:
             xdata = self.get_timestamp(event)
 

sohstationviewer/view/plotting/time_power_square/time_power_squared_widget.py

@@ -69,7 +69,7 @@ class TimePowerSquaredWidget(plotting_widget.PlottingWidget):
         tps_t: float - prompt's time on tps's chart to help rulers on other
             plotting widgets to identify their location
         """
-        self.tps_t = 0
+        self.tps_t = None
         """
         display_top_ticks: flag to display time ticks on top of ax or not
         """