diff --git a/gui/Changelog.txt b/gui/Changelog.txt
index 16d5870..abfc8dc 100644
--- a/gui/Changelog.txt
+++ b/gui/Changelog.txt
@@ -4,9 +4,17 @@
 
 Scyther 1.0-beta6 
 	
-	New features:
+	Big new features:
 
 	* [Gui] Added Mac support (added universal binary)
+	* [Gui] Switched to Scintilla editor component, providing undo
+	and line numbering.
+
+	Other new features:
+
+	* [Backend] Scyther now detects when a read event cannot match
+	with a send event. This significantly helps in reducing errors
+	in the protocol descriptions.
 	* [Language] Added claim parameter for Reachable claim;
 	Reachable,R means that role R should be trusted (as well as the
 	actor), but not any other claim. This can be useful for showing
diff --git a/gui/Gui/Mainwindow.py b/gui/Gui/Mainwindow.py
index e37d786..0d0f78f 100644
--- a/gui/Gui/Mainwindow.py
+++ b/gui/Gui/Mainwindow.py
@@ -6,6 +6,17 @@
 import wx
 import os.path
 
+# Use Scintilla editor?
+useStc = True       # It looks nicer!
+#useStc = False      # It is sometimes buggy!
+
+# Test Scintilla and if it fails, get rid of it
+if useStc:
+    try:
+        import wx.stc as stc
+    except:
+        useStc = False
+
 #---------------------------------------------------------------------------
 
 """ Import scyther-gui components """
@@ -75,6 +86,24 @@ class MainWindow(wx.Frame):
 
         self.firstCommand()
 
+    def GetText(self):
+        """
+        Interface for both types of editor
+        """
+        if useStc:
+            return self.control.GetText()
+        else:
+            return self.control.GetValue()
+
+    def SetText(self,txt):
+        """
+        Interface for both types of editor
+        """
+        if useStc:
+            self.control.SetText(txt)
+        else:
+            self.control.SetValue(txt)
+        
     def CreateInteriorWindowComponents(self):
         ''' Create "interior" window components. In this case it is just a
             simple multiline text control. '''
@@ -92,10 +121,19 @@ class MainWindow(wx.Frame):
 
         # Top: input
         self.top = wx.Notebook(self,-1)
-        self.control = wx.TextCtrl(self.top, style=wx.TE_MULTILINE)
+
+        if useStc:
+            # Scintilla layout with line numbers
+            self.control = stc.StyledTextCtrl(self.top)
+            self.control.SetMarginType(1, stc.STC_MARGIN_NUMBER)
+            self.control.SetMarginWidth(1, 30)
+        else:
+            # Simpler default
+            self.control = wx.TextCtrl(self.top, style=wx.TE_MULTILINE)
+
         if self.load:
             textfile = open(os.path.join(self.dirname, self.filename), 'r')
-            self.control.SetValue(textfile.read())
+            self.SetText(textfile.read())
             os.chdir(self.dirname)
             textfile.close()
         self.top.AddPage(self.control,"Protocol description")
@@ -189,14 +227,14 @@ class MainWindow(wx.Frame):
 
     def OnSave(self, event):
         textfile = open(os.path.join(self.dirname, self.filename), 'w')
-        textfile.write(self.control.GetValue())
+        textfile.write(self.GetText())
         textfile.close()
 
     def OnOpen(self, event):
         if self.askUserForFilename(style=wx.OPEN,
                                    **self.defaultFileDialogOptions()):
             textfile = open(os.path.join(self.dirname, self.filename), 'r')
-            self.control.SetValue(textfile.read())
+            self.SetText(textfile.read())
             textfile.close()
 
     def OnSaveAs(self, event):
@@ -206,7 +244,8 @@ class MainWindow(wx.Frame):
             os.chdir(self.dirname)
 
     def RunScyther(self, mode):
-        s = Scytherthread.ScytherRun(self,mode)
+        spdl = self.GetText()
+        s = Scytherthread.ScytherRun(self,mode,spdl)
 
     def OnVerify(self, event):
         self.RunScyther("verify")
diff --git a/gui/Gui/Scytherthread.py b/gui/Gui/Scytherthread.py
index d83e5c2..bf27fef 100644
--- a/gui/Gui/Scytherthread.py
+++ b/gui/Gui/Scytherthread.py
@@ -444,11 +444,11 @@ class ResultWindow(wx.Frame):
 
 class ScytherRun(object):
 
-    def __init__(self,mainwin,mode):
+    def __init__(self,mainwin,mode,spdl):
 
         self.mainwin = mainwin
         self.mode = mode
-        self.spdl = mainwin.control.GetValue()
+        self.spdl = spdl
         self.verified = False
         self.options = mainwin.settings.ScytherArguments(mode)
         self.main()