diff --git a/SourceGen/MainController.cs b/SourceGen/MainController.cs
index cff8c0a..f005e1c 100644
--- a/SourceGen/MainController.cs
+++ b/SourceGen/MainController.cs
@@ -4187,7 +4187,7 @@ namespace SourceGen {
             string basPathName = Path.GetFullPath(fileDlg.FileName);
             try {
                 data = File.ReadAllBytes(basPathName);
-            } catch (Exception ex) {
+            } catch (IOException ex) {
                 // not expecting this to happen
                 MessageBox.Show(ex.Message);
                 return;
@@ -4201,6 +4201,66 @@ namespace SourceGen {
             showTextDlg.ShowDialog();
         }
 
+        public void Debug_ApplyEditCommands() {
+            OpenFileDialog fileDlg = new OpenFileDialog() {
+                Filter = Res.Strings.FILE_FILTER_SGEC + "|" + Res.Strings.FILE_FILTER_ALL,
+                FilterIndex = 1
+            };
+            if (fileDlg.ShowDialog() != true) {
+                return;
+            }
+
+            string sgecPathName = Path.GetFullPath(fileDlg.FileName);
+            string[] lines;
+            try {
+                lines = File.ReadAllLines(sgecPathName);
+            } catch (IOException ex) {
+                // not expecting this to happen
+                MessageBox.Show(ex.Message);
+                return;
+            }
+
+            ChangeSet cs = new ChangeSet(1);
+
+            List<int> changed = new List<int>(lines.Length);
+
+            string setComment = "set-comment +";
+            foreach (string line in lines) {
+                if (!line.StartsWith(setComment)) {
+                    Debug.WriteLine("Ignoring " + line);
+                    continue;
+                }
+
+                int offset;
+                try {
+                    offset = Convert.ToInt32(line.Substring(setComment.Length, 6), 16);
+                } catch (Exception ex) {
+                    Debug.WriteLine("Failed on " + line);
+                    MessageBox.Show(ex.Message);
+                    return;
+                }
+
+                if (changed.Contains(offset)) {
+                    Debug.WriteLine("Skipping repeated entry +" + offset.ToString("X6"));
+                    continue;
+                }
+
+                string oldComment = mProject.Comments[offset];
+                string newComment = line.Substring(setComment.Length + 7);
+                if (!string.IsNullOrEmpty(oldComment)) {
+                    Debug.WriteLine("Replacing comment +" + offset.ToString("x6") +
+                        " '" + oldComment + "'");
+                }
+
+                UndoableChange uc = UndoableChange.CreateCommentChange(offset,
+                    oldComment, newComment);
+                cs.Add(uc);
+                changed.Add(offset);
+            }
+
+            ApplyUndoableChanges(cs);
+        }
+
         public void Debug_ApplyPlatformSymbols() {
             ChangeSet cs = new ChangeSet(1);
 
diff --git a/SourceGen/Res/Strings.xaml b/SourceGen/Res/Strings.xaml
index a75d4ce..8fd9a64 100644
--- a/SourceGen/Res/Strings.xaml
+++ b/SourceGen/Res/Strings.xaml
@@ -90,6 +90,7 @@ limitations under the License.
     <system:String x:Key="str_FileFilterCsv">CSV files (*.csv)|*.csv</system:String>
     <system:String x:Key="str_FileFilterDis65">SourceGen projects (*.dis65)|*.dis65</system:String>
     <system:String x:Key="str_FileFilterHtml">HTML files (*.html)|*.html</system:String>
+    <system:String x:Key="str_FileFilterSgec">SGEC files (*.sgec)|*.sgec</system:String>
     <system:String x:Key="str_FileFilterSym65">SourceGen symbols (*.sym65)|*.sym65</system:String>
     <system:String x:Key="str_FileFilterText">Text files (*.txt)|*.txt</system:String>
     <system:String x:Key="str_FileInfoFmt">File is {0:N1} KB of raw data.</system:String>
diff --git a/SourceGen/Res/Strings.xaml.cs b/SourceGen/Res/Strings.xaml.cs
index 7ad3343..b4be3ce 100644
--- a/SourceGen/Res/Strings.xaml.cs
+++ b/SourceGen/Res/Strings.xaml.cs
@@ -161,6 +161,8 @@ namespace SourceGen.Res {
             (string)Application.Current.FindResource("str_FileFilterDis65");
         public static string FILE_FILTER_HTML =
             (string)Application.Current.FindResource("str_FileFilterHtml");
+        public static string FILE_FILTER_SGEC =
+            (string)Application.Current.FindResource("str_FileFilterSgec");
         public static string FILE_FILTER_SYM65 =
             (string)Application.Current.FindResource("str_FileFilterSym65");
         public static string FILE_FILTER_TEXT =
diff --git a/SourceGen/RuntimeData/Atari/VisAVG.cs b/SourceGen/RuntimeData/Atari/VisAVG.cs
index 3323708..541a657 100644
--- a/SourceGen/RuntimeData/Atari/VisAVG.cs
+++ b/SourceGen/RuntimeData/Atari/VisAVG.cs
@@ -41,7 +41,7 @@ namespace RuntimeData.Atari {
         private AddressTranslate mAddrTrans;
 
         // Visualization identifiers; DO NOT change or projects that use them will break.
-        private const string VIS_GEN_AVG = "atari-avg";
+        private const string VIS_GEN_AVG = "atari-avg-bz";  // Battlezone, Red Baron
 
         private const string P_OFFSET = "offset";
         private const string P_BASE_ADDR = "baseAddr";
@@ -55,7 +55,7 @@ namespace RuntimeData.Atari {
                     new VisParamDescr("Base address",
                         P_BASE_ADDR, typeof(int), 0x0000, 0xffff, 0, 0x2000),
 
-                    VisWireframe.Param_IsRecentered("Re-center", true),
+                    VisWireframe.Param_IsRecentered("Centered", true),
                 }),
         };
 
@@ -274,6 +274,13 @@ namespace RuntimeData.Atari {
             return (short)val13 >> 3;
         }
 
+        /// <summary>
+        /// Converts a JSR/JMP operand to a file offset.
+        /// </summary>
+        /// <param name="vaddr">AVG address operand.</param>
+        /// <param name="baseAddr">Base address of vector memory.</param>
+        /// <param name="offset">File offset of instruction.</param>
+        /// <returns>False if the target address is outside the file bounds.</returns>
         private bool Branch(int vaddr, int baseAddr, ref int offset) {
             int fileAddr = baseAddr + vaddr * 2;
             int fileOffset = mAddrTrans.AddressToOffset(offset, fileAddr);
diff --git a/SourceGen/WireframeObject.cs b/SourceGen/WireframeObject.cs
index 8739bcb..453fb07 100644
--- a/SourceGen/WireframeObject.cs
+++ b/SourceGen/WireframeObject.cs
@@ -86,6 +86,8 @@ namespace SourceGen {
             }
         }
 
+        public bool VerboseDebug { get; set; }
+
         private bool mIs2d = false;
         private List<Vertex> mVertices = new List<Vertex>();
         private List<Vertex> mPoints = new List<Vertex>();
@@ -257,12 +259,14 @@ namespace SourceGen {
                 ref double ymin, ref double ymax) {
             if (vert.Vec.X < xmin) {
                 xmin = vert.Vec.X;
-            } else if (vert.Vec.X > xmax) {
+            }
+            if (vert.Vec.X > xmax) {
                 xmax = vert.Vec.X;
             }
             if (vert.Vec.Y < ymin) {
                 ymin = vert.Vec.Y;
-            } else if (vert.Vec.Y > ymax) {
+            }
+            if (vert.Vec.Y > ymax) {
                 ymax = vert.Vec.Y;
             }
         }
@@ -291,6 +295,11 @@ namespace SourceGen {
         ///   [-1,1].</returns>
         public List<LineSeg> Generate(int eulerX, int eulerY, int eulerZ,
                 bool doPersp, bool doBfc, bool doRecenter) {
+            if (VerboseDebug) {
+                Debug.WriteLine("Found center=" + mCenterAdjX + "," + mCenterAdjY);
+                Debug.WriteLine("  bigMag=" + mBigMag + " / " + mBigMagRc);
+            }
+
             // overrule flags that don't make sense
             if (mIs2d) {
                 doPersp = doBfc = false;
diff --git a/SourceGen/WpfGui/MainWindow.xaml b/SourceGen/WpfGui/MainWindow.xaml
index 96268f3..fead078 100644
--- a/SourceGen/WpfGui/MainWindow.xaml
+++ b/SourceGen/WpfGui/MainWindow.xaml
@@ -192,6 +192,7 @@ limitations under the License.
             </RoutedUICommand>
 
             <RoutedUICommand x:Key="Debug_ApplesoftToHtmlCmd" Text="Applesoft to HTML..."/>
+            <RoutedUICommand x:Key="Debug_ApplyEditCommandsCmd" Text="Apply Edit Commands..."/>
             <RoutedUICommand x:Key="Debug_ApplyPlatformSymbolsCmd" Text="Apply Platform Symbols"/>
             <RoutedUICommand x:Key="Debug_ExtensionScriptInfoCmd" Text="Extension Script Info..."/>
             <RoutedUICommand x:Key="Debug_ShowAnalysisTimersCmd" Text="Show Analysis Timers"/>
@@ -323,6 +324,8 @@ limitations under the License.
                         Executed="Debug_ApplesoftToHtmlCmd_Executed"/>
         <CommandBinding Command="{StaticResource Debug_ApplyPlatformSymbolsCmd}"
                         CanExecute="IsProjectOpen" Executed="Debug_ApplyPlatformSymbolsCmd_Executed"/>
+        <CommandBinding Command="{StaticResource Debug_ApplyEditCommandsCmd}"
+                        CanExecute="IsProjectOpen" Executed="Debug_ApplyEditCommandsCmd_Executed"/>
         <CommandBinding Command="{StaticResource Debug_ExtensionScriptInfoCmd}"
                         CanExecute="IsProjectOpen" Executed="Debug_ExtensionScriptInfoCmd_Executed"/>
         <CommandBinding Command="{StaticResource Debug_ShowAnalysisTimersCmd}"
@@ -439,6 +442,7 @@ limitations under the License.
                           Command="{StaticResource Debug_ToggleKeepAliveHackCmd}" IsCheckable="True"/>
                 <Separator/>
                 <MenuItem Command="{StaticResource Debug_ApplesoftToHtmlCmd}"/>
+                <MenuItem Command="{StaticResource Debug_ApplyEditCommandsCmd}"/>
                 <MenuItem Command="{StaticResource Debug_ApplyPlatformSymbolsCmd}"/>
             </MenuItem>
         </Menu>
diff --git a/SourceGen/WpfGui/MainWindow.xaml.cs b/SourceGen/WpfGui/MainWindow.xaml.cs
index 834e046..7b540f8 100644
--- a/SourceGen/WpfGui/MainWindow.xaml.cs
+++ b/SourceGen/WpfGui/MainWindow.xaml.cs
@@ -1362,6 +1362,11 @@ namespace SourceGen.WpfGui {
             mMainCtrl.Debug_ApplesoftToHtml();
         }
 
+        private void Debug_ApplyEditCommandsCmd_Executed(object sender,
+                ExecutedRoutedEventArgs e) {
+            mMainCtrl.Debug_ApplyEditCommands();
+        }
+
         private void Debug_ApplyPlatformSymbolsCmd_Executed(object sender,
                 ExecutedRoutedEventArgs e) {
             mMainCtrl.Debug_ApplyPlatformSymbols();