Add a flip diff button

gui/fitDiffFrame.py

@@ -61,12 +61,19 @@ class FitDiffFrame(wx.Frame):
         panel = wx.Panel(self)
         mainSizer = wx.BoxSizer(wx.VERTICAL)
 
-        # Instructions at the top
+        # Instructions and flip button at the top
+        topSizer = wx.BoxSizer(wx.HORIZONTAL)
         instructions = wx.StaticText(
             panel,
             label=_t("Paste fits in EFT format to compare")
         )
-        mainSizer.Add(instructions, 0, wx.ALL | wx.EXPAND, 5)
+        topSizer.Add(instructions, 1, wx.ALL | wx.EXPAND, 5)
+        
+        flipButton = wx.Button(panel, label=_t("Flip"))
+        flipButton.Bind(wx.EVT_BUTTON, self.onFlip)
+        topSizer.Add(flipButton, 0, wx.ALL | wx.ALIGN_CENTER_VERTICAL, 5)
+        
+        mainSizer.Add(topSizer, 0, wx.EXPAND)
 
         # Three panes: Fit 1 | Diff | Fit 2
         panesSizer = wx.BoxSizer(wx.HORIZONTAL)
@@ -127,6 +134,15 @@ class FitDiffFrame(wx.Frame):
         self.updateDiff()
         event.Skip()
 
+    def onFlip(self, event):
+        """Swap Fit 1 and Fit 2."""
+        fit1Value = self.fit1Text.GetValue()
+        fit2Value = self.fit2Text.GetValue()
+        self.fit1Text.SetValue(fit2Value)
+        self.fit2Text.SetValue(fit1Value)
+        self.updateDiff()
+        event.Skip()
+
     def updateDiff(self):
         """Calculate and display the differences between the two fits."""
         self.diffText.Clear()