diff --git a/direct/src/showbase/ShowBase.py b/direct/src/showbase/ShowBase.py
index 35e0568a80..39b8799eb9 100644
--- a/direct/src/showbase/ShowBase.py
+++ b/direct/src/showbase/ShowBase.py
@@ -2626,73 +2626,7 @@ class ShowBase(DirectObject.DirectObject):
 
             # If we have not forced the aspect ratio, let's see if it has
             # changed and update the camera lenses and aspect2d parameters
-            if not self.__configAspectRatio:
-                aspectRatio = self.getAspectRatio()
-                if aspectRatio != self.__oldAspectRatio:
-                    self.__oldAspectRatio = aspectRatio
-                    # Fix up some anything that depends on the aspectRatio
-                    self.camLens.setAspectRatio(aspectRatio)
-                    if aspectRatio < 1:
-                        # If the window is TALL, lets expand the top and bottom
-                        self.aspect2d.setScale(1.0, 1.0, aspectRatio)
-                        self.a2dTop = 1.0 / aspectRatio
-                        self.a2dBottom = - 1.0 / aspectRatio
-                        self.a2dLeft = -1
-                        self.a2dRight = 1.0
-                        # Don't forget 2dp
-                        self.aspect2dp.setScale(1.0, 1.0, aspectRatio)
-                        self.a2dpTop = 1.0 / aspectRatio
-                        self.a2dpBottom = - 1.0 / aspectRatio
-                        self.a2dpLeft = -1
-                        self.a2dpRight = 1.0
-
-                    else:
-                        # If the window is WIDE, lets expand the left and right
-                        self.aspect2d.setScale(1.0 / aspectRatio, 1.0, 1.0)
-                        self.a2dTop = 1.0
-                        self.a2dBottom = -1.0
-                        self.a2dLeft = -aspectRatio
-                        self.a2dRight = aspectRatio
-                        # Don't forget 2dp
-                        self.aspect2dp.setScale(1.0 / aspectRatio, 1.0, 1.0)
-                        self.a2dpTop = 1.0
-                        self.a2dpBottom = -1.0
-                        self.a2dpLeft = -aspectRatio
-                        self.a2dpRight = aspectRatio                        
-
-
-                    # Reposition the aspect2d marker nodes
-                    self.a2dTopCenter.setPos(0, 0, self.a2dTop)
-                    self.a2dBottomCenter.setPos(0, 0, self.a2dBottom)
-                    self.a2dLeftCenter.setPos(self.a2dLeft, 0, 0)
-                    self.a2dRightCenter.setPos(self.a2dRight, 0, 0)                    
-                    self.a2dTopLeft.setPos(self.a2dLeft, 0, self.a2dTop)
-                    self.a2dTopRight.setPos(self.a2dRight, 0, self.a2dTop)
-                    self.a2dBottomLeft.setPos(self.a2dLeft, 0, self.a2dBottom)
-                    self.a2dBottomRight.setPos(self.a2dRight, 0, self.a2dBottom)
-
-                    # Reposition the aspect2d marker nodes
-                    self.a2dTopCenterNs.setPos(0, 0, self.a2dTop)
-                    self.a2dBottomCenterNs.setPos(0, 0, self.a2dBottom)
-                    self.a2dLeftCenterNs.setPos(self.a2dLeft, 0, 0)
-                    self.a2dRightCenterNs.setPos(self.a2dRight, 0, 0)                    
-                    self.a2dTopLeftNs.setPos(self.a2dLeft, 0, self.a2dTop)
-                    self.a2dTopRightNs.setPos(self.a2dRight, 0, self.a2dTop)
-                    self.a2dBottomLeftNs.setPos(self.a2dLeft, 0, self.a2dBottom)
-                    self.a2dBottomRightNs.setPos(self.a2dRight, 0, self.a2dBottom)                    
-
-                    # Reposition the aspect2dp marker nodes
-                    self.a2dpTopCenter.setPos(0, 0, self.a2dpTop)
-                    self.a2dpBottomCenter.setPos(0, 0, self.a2dpBottom)
-                    self.a2dpLeftCenter.setPos(self.a2dpLeft, 0, 0)
-                    self.a2dpRightCenter.setPos(self.a2dpRight, 0, 0)                  
-                    self.a2dpTopLeft.setPos(self.a2dpLeft, 0, self.a2dpTop)
-                    self.a2dpTopRight.setPos(self.a2dpRight, 0, self.a2dpTop)
-                    self.a2dpBottomLeft.setPos(self.a2dpLeft, 0, self.a2dpBottom)
-                    self.a2dpBottomRight.setPos(self.a2dpRight, 0, self.a2dpBottom)
-                    
-                    # If anybody needs to update their GUI, put a callback on this event
-                    messenger.send("aspectRatioChanged")
+            self.adjustWindowAspectRatio(self.getAspectRatio())
             
             # Temporary hasattr for old Pandas
             if not hasattr(win, 'getSbsLeftXSize'):
@@ -2702,6 +2636,78 @@ class ShowBase(DirectObject.DirectObject):
                 self.pixel2d.setScale(2.0 / win.getSbsLeftXSize(), 1.0, 2.0 / win.getSbsLeftYSize())
                 self.pixel2dp.setScale(2.0 / win.getSbsLeftXSize(), 1.0, 2.0 / win.getSbsLeftYSize())
 
+    def adjustWindowAspectRatio(self, aspectRatio):
+        """ This function is normally called internally by
+        windowEvent(), but it may also be called to explicitly adjust
+        the aspect ratio of the render/render2d DisplayRegion, by a
+        class that has redefined these. """
+        
+        if not self.__configAspectRatio:
+            if aspectRatio != self.__oldAspectRatio:
+                self.__oldAspectRatio = aspectRatio
+                # Fix up some anything that depends on the aspectRatio
+                self.camLens.setAspectRatio(aspectRatio)
+                if aspectRatio < 1:
+                    # If the window is TALL, lets expand the top and bottom
+                    self.aspect2d.setScale(1.0, 1.0, aspectRatio)
+                    self.a2dTop = 1.0 / aspectRatio
+                    self.a2dBottom = - 1.0 / aspectRatio
+                    self.a2dLeft = -1
+                    self.a2dRight = 1.0
+                    # Don't forget 2dp
+                    self.aspect2dp.setScale(1.0, 1.0, aspectRatio)
+                    self.a2dpTop = 1.0 / aspectRatio
+                    self.a2dpBottom = - 1.0 / aspectRatio
+                    self.a2dpLeft = -1
+                    self.a2dpRight = 1.0
+
+                else:
+                    # If the window is WIDE, lets expand the left and right
+                    self.aspect2d.setScale(1.0 / aspectRatio, 1.0, 1.0)
+                    self.a2dTop = 1.0
+                    self.a2dBottom = -1.0
+                    self.a2dLeft = -aspectRatio
+                    self.a2dRight = aspectRatio
+                    # Don't forget 2dp
+                    self.aspect2dp.setScale(1.0 / aspectRatio, 1.0, 1.0)
+                    self.a2dpTop = 1.0
+                    self.a2dpBottom = -1.0
+                    self.a2dpLeft = -aspectRatio
+                    self.a2dpRight = aspectRatio                        
+
+                # Reposition the aspect2d marker nodes
+                self.a2dTopCenter.setPos(0, 0, self.a2dTop)
+                self.a2dBottomCenter.setPos(0, 0, self.a2dBottom)
+                self.a2dLeftCenter.setPos(self.a2dLeft, 0, 0)
+                self.a2dRightCenter.setPos(self.a2dRight, 0, 0)                    
+                self.a2dTopLeft.setPos(self.a2dLeft, 0, self.a2dTop)
+                self.a2dTopRight.setPos(self.a2dRight, 0, self.a2dTop)
+                self.a2dBottomLeft.setPos(self.a2dLeft, 0, self.a2dBottom)
+                self.a2dBottomRight.setPos(self.a2dRight, 0, self.a2dBottom)
+
+                # Reposition the aspect2d marker nodes
+                self.a2dTopCenterNs.setPos(0, 0, self.a2dTop)
+                self.a2dBottomCenterNs.setPos(0, 0, self.a2dBottom)
+                self.a2dLeftCenterNs.setPos(self.a2dLeft, 0, 0)
+                self.a2dRightCenterNs.setPos(self.a2dRight, 0, 0)                    
+                self.a2dTopLeftNs.setPos(self.a2dLeft, 0, self.a2dTop)
+                self.a2dTopRightNs.setPos(self.a2dRight, 0, self.a2dTop)
+                self.a2dBottomLeftNs.setPos(self.a2dLeft, 0, self.a2dBottom)
+                self.a2dBottomRightNs.setPos(self.a2dRight, 0, self.a2dBottom)                    
+
+                # Reposition the aspect2dp marker nodes
+                self.a2dpTopCenter.setPos(0, 0, self.a2dpTop)
+                self.a2dpBottomCenter.setPos(0, 0, self.a2dpBottom)
+                self.a2dpLeftCenter.setPos(self.a2dpLeft, 0, 0)
+                self.a2dpRightCenter.setPos(self.a2dpRight, 0, 0)                  
+                self.a2dpTopLeft.setPos(self.a2dpLeft, 0, self.a2dpTop)
+                self.a2dpTopRight.setPos(self.a2dpRight, 0, self.a2dpTop)
+                self.a2dpBottomLeft.setPos(self.a2dpLeft, 0, self.a2dpBottom)
+                self.a2dpBottomRight.setPos(self.a2dpRight, 0, self.a2dpBottom)
+
+                # If anybody needs to update their GUI, put a callback on this event
+                messenger.send("aspectRatioChanged")
+        
     def userExit(self):
         # The user has requested we exit the program.  Deal with this.
         if self.exitFunc: