Correctly clear out the fitting view from a tab when it gets deleted

gui/fittingView.py

@@ -84,3 +84,5 @@ class FittingView(wx.ListCtrl):
         self.activeFitID = fitID
         if fitID == None:
             self.Hide()
+        else:
+            self.Show()

gui/multiSwitch.py

@@ -69,6 +69,9 @@ class MultiSwitch(wx.Notebook):
             self.setTabTitle(i, None)
             self.SetPageImage(i, -1)
             self.ImageList.Remove(self.GetPageImage(i))
+            page = self.GetPage(i)
+            if page.type == "fit":
+                page.view.changeFit(None)
 
     def checkRemove(self, event):
         tab, _ = self.HitTest(event.Position)