Add Event Sources:event_sources

- Add source property in Action and EventFilter
- Change TPropContainer contructor to accept keyword arguments and set
  properties that were given
- Change every single TPropContainer subclass constructor to accept
  kwargs and pass them on to super init
- Add a "null" option for TStringProperty
Use Event Sources:
- Make the probe require a source property to install or subscribe
- Have ProbeProxy install and subscribe return a prefixed address
- Make update, uninstall and unsubsribe extract the prefix from the
  address
- Have the TutorialRunner set a source on actions/events before
  installing/subscribing instead of setting current activity on
  ProbeManager
Test Event Sources:
- Change the tests according to the new constructors and behaviors

1 files changed, 4 insertions, 9 deletions

diff --git a/addons/messagebuttonnext.py b/addons/messagebuttonnext.py
index 74ce1bb..058ef41 100644
--- a/addons/messagebuttonnext.py
+++ b/addons/messagebuttonnext.py
@@ -38,23 +38,18 @@ class MessageButtonNext(EventFilter):
     # set padding
     padding = 40
 
-    def __init__(self, message=None, position=None, center_pos=False):
+    def __init__(self, **kwargs):
         """Constructor.
-
+        Accepted keyword arguments:
         @param message message to display
         @param position message position
         """
-        super(MessageButtonNext,self).__init__()
+        super(MessageButtonNext,self).__init__(**kwargs)
 
-        if position:
-            self.position = position
-        else:
+        if not self.position:
             # TODO: to be removed when creator supports editing properties on events
             self.position = (300, 200)
 
-        if message:
-            self.message = message
-
         self.overlay = None
         self.msgnext = None