Index: pyconquer.py
===================================================================
--- pyconquer.py (revision 44)
+++ pyconquer.py (revision 45)
@@ -46,4 +46,6 @@
     
     def __init__(self, fileregex=".*", events=('call', 'return', 'exception')):
+        self.active = False
+        
         self.columns = {}
         self.currentcol = Column(-1)
@@ -63,35 +65,31 @@
         self.watches = {}
     
-    def _get_events(self):
-        return self._events
-    def _set_events(self, newvalue):
-        if 'line' in newvalue:
-            for e in c_events:
-                if e in newvalue:
-                    raise ValueError("Tracer.events cannot contain both "
-                                     "'line' and 'c_*' events")
-        self._events = newvalue
-    events = property(_get_events, _set_events)
-    
     def start(self):
         self.out.write("\n\n________ pyconquer tracing started ________\n")
         self.write_watches()
+        
         self._using_profile_hook = False
         for e in c_events:
             if e in self.events:
-                # Must use the profile hook, since only it supports C events.
-                threading.setprofile(self.hook)
-                sys.setprofile(self.hook)
-                self._using_profile_hook = False
+                # Must also use the profile hook,
+                # since tracing does not support C events.
+                threading.setprofile(self.profhook)
+                sys.setprofile(self.profhook)
+                self._using_profile_hook = True
                 break
-        else:
-            # Use the trace hook, since it is easier to clean up
-            threading.settrace(self.hook)
-            sys.settrace(self.hook)
+        
+        # Set the trace hook for all events other than C events.
+        # (it's easier to clean up nicely).
+        threading.settrace(self.hook)
+        sys.settrace(self.hook)
+        
+        self.active = True
     
     def stop(self):
+        self.active = False
+        
         if threading._trace_hook == self.hook:
             threading.settrace(None)
-        if threading._profile_hook == self.hook:
+        if threading._profile_hook == self.profhook:
             threading.setprofile(None)
         
@@ -106,5 +104,12 @@
         self.out.write("\n\n________ pyconquer tracing stopped ________\n")
     
+    def profhook(self, frame, event, arg):
+        if not event.startswith("c_"):
+            return
+        return self.hook(frame, event, arg)
+    
     def hook(self, frame, event, arg):
+        if not self.active:
+            return
         self._mutex.acquire(True)
         try:
@@ -112,4 +117,6 @@
             if event in self.events:
                 filename = frame.f_code.co_filename
+                
+                # Deny tracing this module itself.
                 if r"\pyconquer.py" in filename:
                     return self.hook
@@ -168,5 +175,11 @@
         self.write_col("> %s (%s:%s)" % (frame.f_code.co_name,
                                          scope_name(frame), frame.f_lineno))
-    process_c_call = process_call
+    
+    def process_c_call(self, frame, arg):
+        # arg should be the called C function
+        self.currentcol.indent += 1
+        self.write_col(">>%s (%s:%s): %s" % (frame.f_code.co_name,
+                                             scope_name(frame),
+                                             frame.f_lineno, arg))
     
     def process_return(self, frame, arg):
@@ -178,5 +191,11 @@
                                            frame.f_lineno, retval))
         self.currentcol.indent -= 1
-    process_c_return = process_return
+    
+    def process_c_return(self, frame, arg):
+        # arg should be the called C function
+        self.write_col("<<%s (%s:%s): %s" % (frame.f_code.co_name,
+                                             scope_name(frame),
+                                             frame.f_lineno, arg))
+        self.currentcol.indent -= 1
     
     def process_exception(self, frame, arg):
@@ -189,5 +208,10 @@
                                              scope_name(frame),
                                              frame.f_lineno, retval))
-    process_c_exception = process_exception
+    
+    def process_c_exception(self, frame, arg):
+        # arg should be the called C function
+        self.write_col("EE%s (%s:%s): %s" % (frame.f_code.co_name,
+                                             scope_name(frame),
+                                             frame.f_lineno, arg))
     
     def process_line(self, frame, arg):
Index: test_pyconquer.py
===================================================================
--- test_pyconquer.py (revision 44)
+++ test_pyconquer.py (revision 45)
@@ -7,4 +7,5 @@
 except ImportError:
     from StringIO import StringIO
+import sys
 import threading
 import unittest
@@ -45,29 +46,61 @@
 
 [ MainThread ]
-* testNormalFlow (test_pyconquer:35) New Thread: Thread-1
+* testNormalFlow (test_pyconquer:36) New Thread: Thread-1
 
         [ Thread-1 ]
-        > inc (test_pyconquer:31)
+        > inc (test_pyconquer:32)
         = c.value: 1
-        < inc (test_pyconquer:33)
+        < inc (test_pyconquer:34)
         X Thread terminated: Thread-1
 
 [ MainThread ]
-* testNormalFlow (test_pyconquer:35) New Thread: Thread-2
+* testNormalFlow (test_pyconquer:36) New Thread: Thread-2
 
         [ Thread-2 ]
-        > inc (test_pyconquer:31)
+        > inc (test_pyconquer:32)
         = c.value: 2
-        < inc (test_pyconquer:33)
+        < inc (test_pyconquer:34)
         X Thread terminated: Thread-2
 
 [ MainThread ]
-* testNormalFlow (test_pyconquer:35) New Thread: Thread-3
+* testNormalFlow (test_pyconquer:36) New Thread: Thread-3
 
         [ Thread-3 ]
-        > inc (test_pyconquer:31)
+        > inc (test_pyconquer:32)
         = c.value: 3
-        < inc (test_pyconquer:33)
+        < inc (test_pyconquer:34)
         X Thread terminated: Thread-3
+
+________ pyconquer tracing stopped ________
+""")
+    
+    def testCEvents(self):
+        c = Counter()
+        tr = pyconquer.Tracer(events=('call', 'return', 'exception',
+                                      'c_call', 'c_return', 'c_exception',
+                                      ))
+        tr.out = StringIO()
+        try:
+            tr.start()
+            # Trace c_call and c_return
+            c.value = sys.getrecursionlimit()
+            # Raise a c_exception
+            try:
+                c.value = chr('a')
+            except TypeError:
+                pass
+        finally:
+            tr.stop()
+        
+        self.assertEqual(tr.out.getvalue(), """
+
+________ pyconquer tracing started ________
+
+
+[ MainThread ]
+>>testCEvents (test_pyconquer:86): <built-in function getrecursionlimit>
+<<testCEvents (test_pyconquer:86): <built-in function getrecursionlimit>
+>>testCEvents (test_pyconquer:89): <built-in function chr>
+EEtestCEvents (test_pyconquer:89): <built-in function chr>
 
 ________ pyconquer tracing stopped ________