diff --git a/src/Mod/Path/Gui/Resources/preferences/PathJob.ui b/src/Mod/Path/Gui/Resources/preferences/PathJob.ui
index f7ab52128..17e82cab4 100644
--- a/src/Mod/Path/Gui/Resources/preferences/PathJob.ui
+++ b/src/Mod/Path/Gui/Resources/preferences/PathJob.ui
@@ -70,6 +70,9 @@
       </item>
       <item row="1" column="1">
        <widget class="QComboBox" name="defaultPostProcessor">
+        <property name="toolTip">
+         <string>&lt;html&gt;&lt;head/&gt;&lt;body&gt;&lt;p&gt;Select one of the post processors as the default.&lt;/p&gt;&lt;/body&gt;&lt;/html&gt;</string>
+        </property>
         <property name="prefEntry" stdset="0">
          <string>DefaultPostProcessor</string>
         </property>
@@ -106,7 +109,14 @@
        </widget>
       </item>
       <item row="0" column="1">
-       <widget class="QListWidget" name="postProcessorList"/>
+       <widget class="QListWidget" name="postProcessorList">
+        <property name="mouseTracking">
+         <bool>true</bool>
+        </property>
+        <property name="toolTip">
+         <string>&lt;html&gt;&lt;head/&gt;&lt;body&gt;&lt;p&gt;It doesn't seem there are any post processor scripts installed. Pleas add some into your macro directory and make sure the file name ends with &amp;quot;_post.py&amp;quot;.&lt;/p&gt;&lt;/body&gt;&lt;/html&gt;</string>
+        </property>
+       </widget>
       </item>
      </layout>
     </widget>
diff --git a/src/Mod/Path/PathScripts/PathPreferencesPathJob.py b/src/Mod/Path/PathScripts/PathPreferencesPathJob.py
index fd423c4dc..d9581de29 100644
--- a/src/Mod/Path/PathScripts/PathPreferencesPathJob.py
+++ b/src/Mod/Path/PathScripts/PathPreferencesPathJob.py
@@ -34,10 +34,9 @@ class Page:
 
         self.postProcessorDefaultTooltip = self.form.defaultPostProcessor.toolTip()
         self.postProcessorArgsDefaultTooltip = self.form.defaultPostProcessorArgs.toolTip()
-        self.tooltip = { }
+        self.processor = { }
 
     def saveSettings(self):
-        print("saveSettings")
         processor = str(self.form.defaultPostProcessor.currentText())
         args = str(self.form.defaultPostProcessorArgs.text())
         blacklist = []
@@ -48,7 +47,6 @@ class Page:
         PostProcessor.saveDefaults(processor, args, blacklist)
 
     def loadSettings(self):
-        print("loadSettings")
         self.form.defaultPostProcessor.addItem("")
         blacklist = PostProcessor.blacklist()
         for processor in PostProcessor.all():
@@ -71,12 +69,34 @@ class Page:
         self.form.defaultPostProcessorArgs.setText(PostProcessor.defaultArgs())
 
         self.form.postProcessorList.itemEntered.connect(self.setProcessorListTooltip)
+        self.form.defaultPostProcessor.currentIndexChanged.connect(self.updateDefaultPostProcessorToolTip)
+
+    def getPostProcessor(self, name):
+        if not name in self.processor.keys():
+            processor = PostProcessor.load(name)
+            self.processor[name] = processor
+            return processor
+        return self.processor[name]
+
+    def setPostProcessorTooltip(self, widget, name, default):
+        processor = self.getPostProcessor(name)
+        if processor.tooltip:
+            widget.setToolTip(processor.tooltip)
+        else:
+            widget.setToolTip(default)
 
     def setProcessorListTooltip(self, item):
-        if not item.text() in self.tooltip.keys():
-            processor = PostProcessor.load(item.text())
-            if processor.tooltip:
-                self.form.postProcessorList.setToolTip(processor.tooltip)
-            else:
-                self.form.postProcessorList.setToolTip('')
+        self.setPostProcessorTooltip(self.form.postProcessorList, item.text(), '')
 
+    def updateDefaultPostProcessorToolTip(self):
+        name = str(self.form.defaultPostProcessor.currentText())
+        if name:
+            self.setPostProcessorTooltip(self.form.defaultPostProcessor, name, self.postProcessorDefaultTooltip)
+            processor = self.getPostProcessor(name)
+            if processor.tooltipArgs:
+                self.form.defaultPostProcessorArgs.setToolTip(processor.tooltipArgs)
+            else:
+                self.form.defaultPostProcessorArgs.setToolTip(self.postProcessorArgsDefaultTooltip)
+        else:
+            self.form.defaultPostProcessor.setToolTip(self.postProcessorDefaultTooltip)
+            self.form.defaultPostProcessorArgs.setToolTip(self.postProcessorArgsDefaultTooltip)
diff --git a/src/Mod/Path/PathScripts/centroid_post.py b/src/Mod/Path/PathScripts/centroid_post.py
index f95ca1a69..dbae475d9 100644
--- a/src/Mod/Path/PathScripts/centroid_post.py
+++ b/src/Mod/Path/PathScripts/centroid_post.py
@@ -26,7 +26,6 @@ TOOLTIP=''' example post for Centroid CNC mill'''
 import FreeCAD
 import datetime
 now = datetime.datetime.now()
-originfile = FreeCAD.ActiveDocument.FileName
 import Path, PathScripts
 from PathScripts import PostUtils
 
@@ -46,7 +45,7 @@ COMMENT= ';' #centroid control comment symbol
 HEADER = ""
 HEADER += ";Exported by FreeCAD\n"
 HEADER += ";Post Processor: " + __name__ +"\n"
-HEADER += ";CAM file: "+originfile+"\n"
+HEADER += ";CAM file: %s\n"
 HEADER += ";Output Time:"+str(now)+"\n"
 
 TOOLRETURN = '''M5 M25
@@ -89,7 +88,7 @@ def export(selection,filename,argstring):
         print "No machine found in this selection"
 
     gcode =''
-    gcode+= HEADER
+    gcode+= HEADER % (FreeCAD.ActiveDocument.FileName)
     gcode+= SAFETYBLOCK
     gcode+= UNITS+'\n'