Merge pull request #27721 from martyngigg/27717-float-conversion-warnings-plotoptions

Avoid new implicit float to int conversion warnings in Python 3.8

qt/python/mantidqt/widgets/plotconfigdialog/legendtabwidget/presenter.py

@@ -56,7 +56,7 @@ class LegendTabWidgetPresenter:
 
         # Converts alpha value (opacity value between 0 and 1) to transparency percentage.
         if int(matplotlib.__version__[0]) >= 2:
-            transparency = 100-(legend_props.transparency*100)
+            transparency = int(100 - (legend_props.transparency*100))
             self.view.set_transparency_spin_box(transparency)
             self.view.set_transparency_slider(transparency)
         self.view.set_entries_font(legend_props.entries_font)