Rework how we handle all modal dialogs

gui/builtinShipBrowser/fitItem.py

@@ -344,15 +344,14 @@ class FitItem(SFItem.SFBrowserItem):
         if mstate.GetModifiers() == wx.MOD_SHIFT or mstate.MiddleIsDown():
             self.deleteFit()
         else:
-            dlg = wx.MessageDialog(
+            with wx.MessageDialog(
                 self,
                 "Do you really want to delete this fit?",
                 "Confirm Delete",
                 wx.YES | wx.NO | wx.ICON_QUESTION
-            )
-
-            if dlg.ShowModal() == wx.ID_YES:
-                self.deleteFit()
+            ) as dlg:
+                if dlg.ShowModal() == wx.ID_YES:
+                    self.deleteFit()
 
     def deleteFit(self, event=None):
         pyfalog.debug("Deleting ship fit.")