diff --git a/panda/src/display/graphicsWindow.cxx b/panda/src/display/graphicsWindow.cxx
index eb5c7c1b55..c53164f88b 100644
--- a/panda/src/display/graphicsWindow.cxx
+++ b/panda/src/display/graphicsWindow.cxx
@@ -931,11 +931,3 @@ do_determine_display_regions() {
     }
   }
 }
-
-void GraphicsWindow::
-get_framebuffer_format(PixelBuffer::Type &fb_type, PixelBuffer::Format &fb_format) {
-    display_cat.warning() << "get_framebuffer_format() unimplemented by " << get_type() << endl; 
-    
-    fb_type = PixelBuffer::T_unsigned_byte;
-    fb_format = PixelBuffer::F_rgb;
-}
diff --git a/panda/src/display/graphicsWindow.h b/panda/src/display/graphicsWindow.h
index 90b750b9b0..80dbaef80e 100644
--- a/panda/src/display/graphicsWindow.h
+++ b/panda/src/display/graphicsWindow.h
@@ -104,12 +104,12 @@ public:
   bool has_button_event(int device) const;
   ButtonEvent get_button_event(int device);
 
-  virtual void get_framebuffer_format(PixelBuffer::Type &fb_type, PixelBuffer::Format &fb_format);
-
-public:
   virtual int verify_window_sizes(int numsizes, int *dimen);
+
   PT(DisplayRegion) make_scratch_display_region(int x_size, int y_size) const;
 
+public:
+  // These are not intended to be called directly by the user.
   INLINE void win_display_regions_changed();
 
 public:
diff --git a/panda/src/dxgsg8/wdxGraphicsWindow8.cxx b/panda/src/dxgsg8/wdxGraphicsWindow8.cxx
index 1801ee1d58..1c3feaf526 100644
--- a/panda/src/dxgsg8/wdxGraphicsWindow8.cxx
+++ b/panda/src/dxgsg8/wdxGraphicsWindow8.cxx
@@ -199,8 +199,76 @@ release_gsg() {
   if (_gsg != (GraphicsStateGuardian *)NULL) {
     GraphicsWindow::release_gsg();
   }
+} 
+
+////////////////////////////////////////////////////////////////////
+//     Function: wdxGraphicsWindow8::verify_window_sizes
+//       Access: Public, Virtual
+//  Description: Determines which of the indicated window sizes are
+//               supported by available hardware (e.g. in fullscreen
+//               mode).
+//
+//               On entry, dimen is an array containing contiguous x,y
+//               pairs specifying possible display sizes; it is
+//               numsizes*2 words long.  The function will zero out
+//               any invalid x,y size pairs.  The return value is the
+//               number of valid sizes that were found.
+////////////////////////////////////////////////////////////////////
+int wdxGraphicsWindow8::
+verify_window_sizes(int numsizes, int *dimen) {
+  // unfortunately this only works AFTER you make the window
+  // initially, so its really mostly useful for resizes only
+  assert(IS_VALID_PTR(_dxgsg));
+
+  int num_valid_modes = 0;
+
+  // not requesting same refresh rate since changing res might not
+  // support same refresh rate at new size
+
+  int *pCurDim = dimen;
+
+  for (int i=0; i < numsizes; i++, pCurDim += 2) {
+    int x_size = pCurDim[0];
+    int y_size = pCurDim[1];
+
+    bool bIsGoodMode = false;
+    bool CouldntFindAnyValidZBuf;
+    D3DFORMAT newPixFmt = D3DFMT_UNKNOWN;
+
+    if (special_check_fullscreen_resolution(x_size, y_size)) {
+      // bypass the test below for certain cards we know have valid modes
+      bIsGoodMode=true;
+
+    } else {
+      if (_dxgsg->scrn.bIsLowVidMemCard) {
+        bIsGoodMode = ((x_size == 640) && (y_size == 480));
+      } else  {
+        search_for_valid_displaymode(x_size, y_size, _dxgsg->scrn.PresParams.EnableAutoDepthStencil != false,
+                                     IS_STENCIL_FORMAT(_dxgsg->scrn.PresParams.AutoDepthStencilFormat),
+                                     &_dxgsg->scrn.SupportedScreenDepthsMask,
+                                     &CouldntFindAnyValidZBuf, &newPixFmt);
+        bIsGoodMode = (newPixFmt != D3DFMT_UNKNOWN);
+      }
+    }
+
+    if (bIsGoodMode) {
+      num_valid_modes++;
+    } else {
+      // tell caller the mode is invalid
+      pCurDim[0] = 0;
+      pCurDim[1] = 0;
+    }
+
+    if (wdxdisplay8_cat.is_spam()) {
+      wdxdisplay8_cat.spam()
+        << "Fullscrn Mode (" << x_size << "," << y_size << ")\t" 
+        << (bIsGoodMode ? "V" : "Inv") <<"alid\n";
+    }
+  }
+
+  return num_valid_modes;
 }
- 
+
 ////////////////////////////////////////////////////////////////////
 //     Function: wdxGraphicsWindow8::begin_frame
 //       Access: Public, Virtual
diff --git a/panda/src/dxgsg8/wdxGraphicsWindow8.h b/panda/src/dxgsg8/wdxGraphicsWindow8.h
index 02248e9c86..815bdbb717 100644
--- a/panda/src/dxgsg8/wdxGraphicsWindow8.h
+++ b/panda/src/dxgsg8/wdxGraphicsWindow8.h
@@ -45,6 +45,8 @@ public:
   virtual void make_gsg();
   virtual void release_gsg();
 
+  virtual int verify_window_sizes(int numsizes, int *dimen);
+
   virtual bool begin_frame();
   virtual void end_flip();