diff --git a/windows/src/developer/TIKE/child/UfrmDebug.pas b/windows/src/developer/TIKE/child/UfrmDebug.pas
index 25cf44da90..10819d5015 100644
--- a/windows/src/developer/TIKE/child/UfrmDebug.pas
+++ b/windows/src/developer/TIKE/child/UfrmDebug.pas
@@ -57,20 +57,40 @@ unit UfrmDebug;  // I3323  // I3306
 interface
 
 uses
-  Windows, Messages, SysUtils, Classes, Graphics, Controls, Forms, Dialogs,
-  ExtCtrls, Grids, ComCtrls, CaptionPanel, Buttons,
-  StdCtrls, debugging, debugkeyboard, UfrmMDIEditor, PaintPanel, Menus,
-  HintLabel, debugdeadkeys, UserMessages,
-  UframeTextEditor,
+  System.Classes,
+  System.Generics.Collections,
+  System.SysUtils,
   Vcl.AppEvnts,
+  Vcl.Buttons,
+  Vcl.ComCtrls,
+  Vcl.Controls,
+  Vcl.Dialogs,
+  Vcl.ExtCtrls,
+  Vcl.Forms,
+  Vcl.Graphics,
+  Vcl.Grids,
+  Vcl.Menus,
+  Vcl.StdCtrls,
+  Winapi.Messages,
+  Winapi.Windows,
+
+  CaptionPanel,
+  debugdeadkeys,
+  debugging,
+  debugkeyboard,
   DebugUtils,
-  keymanapi_TLB, msctf, UfrmTike,
-  KeymanDeveloperDebuggerMemo;
+  HintLabel,
+  PaintPanel,
+  keymanapi_TLB,
+  KeymanDeveloperDebuggerMemo,
+  msctf,
+  UframeTextEditor,
+  UfrmMDIEditor,
+  UfrmTike,
+  UserMessages;
 
 type
-  TUpdateParColourEvent = procedure(Sender: TObject; ALine: Integer; ALineType: TParColourLineType) of object;
-
-  TBreakpointRange = 0..99;
+  TDebugLineEvent = procedure(Sender: TObject; ALine: Integer) of object;
 
   TDebugUIStatus = (duiInvalid, duiPaused, duiFocusedForInput, duiReadyForInput, duiReceivingEvents, duiDebugging,
     duiClosing, duiDebuggingOutput, duiTest);
@@ -87,6 +107,8 @@ type
     property TrueLineNumber: Integer read GetTrueLineNumber write SetTrueLineNumber;
   end;
 
+  TDebugBreakpoints = class(TObjectList<TDebugBreakpoint>);
+
   TfrmDebug = class(TTikeForm)
     memo: TKeymanDeveloperDebuggerMemo;
     mnuPopup: TPopupMenu;   // I4796
@@ -115,7 +137,7 @@ type
   private
 
     FDebugVisible: Boolean;
-    FBreakpoint: array[TBreakpointRange] of TDebugBreakpoint;
+    FBreakpoints: TDebugBreakpoints;
     FRunning, FFoundBreakpoint, FForceKeyboard: Boolean;
     FFileName: string;
     //FEditor: TfrmTikeEditor;
@@ -163,8 +185,6 @@ type
 
     procedure KeymanGetContext(var Message: TMessage);
 
-    procedure UpdateParColour(Line: Integer; LineType: TParColourLineType);
-
     procedure AddDebug(s: WideString);
 
     { Debug panel functions }
@@ -174,10 +194,13 @@ type
   private
     FANSITest: Boolean;
     FEditorMemo: TframeTextEditor;
-    FOnUpdateParColour: TUpdateParColourEvent;
+
     FDebugFileName: WideString;
     FSingleStepMode: Boolean;
     FCanDebug: Boolean;
+    FOnUpdateExecutionPoint: TDebugLineEvent;
+    FOnClearBreakpoint: TDebugLineEvent;
+    FOnSetBreakpoint: TDebugLineEvent;
     procedure SetANSITest(const Value: Boolean);
     procedure UpdateANSITest;
     procedure ClearDeadkeys;
@@ -216,13 +239,14 @@ type
 
     procedure SetBreakpoint(ALine: Integer);
     procedure ClearBreakpoint(ALine: Integer);
+    procedure ToggleBreakpoint(ALine: Integer);
 
     function IsBreakPointLine(ALine: Integer): Boolean;
     function IsExecutionPointLine(ALine: Integer): Boolean;
 
     function GetDebugKeyboard: TDebugKeyboard;
 
-    property CanDebug: Boolean read FCanDebug write FCanDebug; 
+    property CanDebug: Boolean read FCanDebug write FCanDebug;
     property UIStatus: TDebugUIStatus read FUIStatus write SetUIStatus;
 
     property SingleStepMode: Boolean read FSingleStepMode write SetSingleStepMode;
@@ -250,7 +274,9 @@ type
 
     property CurrentEvent: TDebugEvent read GetCurrentEvent;
 
-    property OnUpdateParColour: TUpdateParColourEvent read FOnUpdateParColour write FOnUpdateParColour;
+    property OnSetBreakpoint: TDebugLineEvent read FOnSetBreakpoint write FOnSetBreakpoint;
+    property OnClearBreakpoint: TDebugLineEvent read FOnClearBreakpoint write FOnClearBreakpoint;
+    property OnUpdateExecutionPoint: TDebugLineEvent read FOnUpdateExecutionPoint write FOnUpdateExecutionPoint;
   end;
 
 implementation
@@ -317,6 +343,7 @@ begin
 //  InitMSCTF;   // I3655
 
   TDebugUtils.GetActiveTSFProfile(FLastActiveProfile);   // I4331
+  FBreakpoints := TDebugBreakpoints.Create;
 
   FExecutionPointLine := -1;
   //InitControlCaptions;
@@ -331,11 +358,9 @@ begin
 end;
 
 procedure TfrmDebug.FormDestroy(Sender: TObject);
-var
-  i: TBreakpointRange;
 begin
   ResetDebug;
-  for i := Low(TBreakpointRange) to High(TBreakpointRange) do FBreakpoint[i].Free;
+  FBreakpoints.Free;
   FEvents.Free;
   //UninitControlCaptions;
   //UninitSystemKeyboard;
@@ -722,7 +747,7 @@ end;
 procedure TfrmDebug.WMUSERUpdateForceKeyboard(var Message: TMessage);   // I4767
     procedure FailTidyUp;
     begin
-      Windows.SetFocus(0);
+      Winapi.Windows.SetFocus(0);
       HideDebugForm;
       FForceKeyboard := False;
     end;
@@ -763,8 +788,8 @@ begin
       if FWasStarted then  // I3283   // I3503
       begin
         // Give Keyman Engine a chance to correctly attach focus after it starts
-        Windows.SetFocus(0);
-        Windows.SetFocus(memo.Handle);
+        Winapi.Windows.SetFocus(0);
+        Winapi.Windows.SetFocus(memo.Handle);
         Exit;
       end;
 
@@ -784,7 +809,7 @@ begin
         {Keyman_Exit; I3283   // I3503
         if not Keyman_Initialise(Application.MainForm.Handle, True) or not Keyman_ForceKeyboard(FFileName) then
         begin}
-          Windows.SetFocus(0);
+          Winapi.Windows.SetFocus(0);
           HideDebugForm;
           ShowMessage('Unable to start debugger - please make sure that Keyman Developer is correctly installed (the error code was '+IntToHex(FLastError, 8)+').');  // I3173   // I3504
           //(Editor as TfrmEditor).HideDebugForm;
@@ -1017,59 +1042,49 @@ end;
 
 procedure TfrmDebug.SetBreakpoint(ALine: Integer);
 var
-  i: TBreakpointRange;
-  j: Integer;
+  b: TDebugBreakpoint;
 begin
-  j := -1;
-  for i := Low(TBreakpointRange) to High(TBreakpointRange) do
-  begin
-    if Assigned(FBreakpoint[i]) then
-    begin
-      if (FBreakpoint[i].TrueLineNumber = ALine) then Exit;
-    end
-    else if j = -1 then j := i;
-  end;
+  for b in FBreakpoints do
+    if b.TrueLineNumber = ALine then
+      Exit;
 
-  if j = -1 then
-  begin
-    ShowMessage('You can only have a maximum of '+
-      IntToStr(High(TBreakpointRange)-Low(TBreakpointRange))+' breakpoints.');
-    Exit;
-  end;
+  b := TDebugBreakpoint.Create(EditorMemo);
+  b.TrueLineNumber := ALine;
+  FBreakpoints.Add(b);
 
-  FBreakpoint[j] := TDebugBreakpoint.Create(EditorMemo);
-  FBreakpoint[j].TrueLineNumber := ALine;
-  UpdateParColour(ALine, pcltBreakpoint);
+  if Assigned(FOnSetBreakpoint) then
+    FOnSetBreakpoint(Self, ALine);
 end;
 
 procedure TfrmDebug.ClearBreakpoint(ALine: Integer);
 var
-  i: TBreakpointRange;
+  b: TDebugBreakpoint;
 begin
-  for i := Low(TBreakpointRange) to High(TBreakpointRange) do
-    if Assigned(FBreakpoint[i]) and (FBreakpoint[i].TrueLineNumber = ALine) then
+  for b in FBreakpoints do
+    if b.TrueLineNumber = ALine then
     begin
-      FBreakpoint[i].Free;
-      FBreakpoint[i] := nil;
-      if IsExecutionPointLine(ALine)
-        then UpdateParColour(ALine, pcltExecutionPoint)
-        else UpdateParColour(ALine, pcltNone);
+      FBreakpoints.Remove(b);
+      if Assigned(FOnClearBreakpoint) then
+        FOnClearBreakpoint(Self, ALine);
       Exit;
     end;
 end;
 
+procedure TfrmDebug.ToggleBreakpoint(ALine: Integer);
+begin
+  if IsBreakpointLine(ALine)
+    then ClearBreakpoint(ALine)
+    else SetBreakpoint(ALine)
+end;
+
 function TfrmDebug.IsBreakPointLine(ALine: Integer): Boolean;
 var
-  i: Integer;
+  b: TDebugBreakpoint;
 begin
-  Result := True;
-  for i := Low(TBreakpointRange) to High(TBreakpointRange) do
-  begin
-    if FBreakpoint[i] <> nil then
-      if FBreakpoint[i].TrueLineNumber = ALine then
-        Exit;
-  end;
-  Result := False;
+  for b in FBreakpoints do
+    if b.TrueLineNumber = ALine then
+      Exit(True);
+  Exit(False);
 end;
 
 {-------------------------------------------------------------------------------
@@ -1082,28 +1097,21 @@ begin
 end;
 
 procedure TfrmDebug.SetExecutionPointLine(ALine: Integer);
-var
-  oldline: Integer;
 begin
-  oldline := FExecutionPointLine;
   FExecutionPointLine := ALine;
-  if IsBreakPointLine(oldline)
-    then UpdateParColour(oldline, pcltBreakpoint)
-    else UpdateParColour(oldline, pcltNone);
-  if FRunning then Exit;
-  if FExecutionPointLine >= 0 then
-    UpdateParColour(FExecutionPointLine, pcltExecutionPoint);
+  if FRunning and (FExecutionPointLine >= 0) then Exit;
+  if Assigned(FOnUpdateExecutionPoint) then
+    FOnUpdateExecutionPoint(Self, ALine);
 end;
 
 procedure TfrmDebug.ListBreakpoints;
 var
-  i: Integer;
+  b: TDebugBreakpoint;
 begin
   memo.Clear;
-  //frmDebugStatus.DeadKeys.ClearDeadkeys;  I1699
-  for i := 0 to 99 do
-    if Assigned(FBreakPoint[i]) and (FBreakpoint[i].TrueLineNumber >= 0) then
-      UpdateParColour(FBreakpoint[i].TrueLineNumber, pcltBreakpoint);
+  for b in FBreakpoints do
+    if Assigned(FOnSetBreakpoint) then
+      FOnSetBreakpoint(Self, b.TrueLineNumber);
 end;
 
 
@@ -1178,12 +1186,6 @@ begin
   (frmDebugStatus as TfrmDebugStatus).DisplayFont := FFont;
 end;
 
-procedure TfrmDebug.UpdateParColour(Line: Integer; LineType: TParColourLineType);
-begin
-  if Assigned(FOnUpdateParColour) then
-    FOnUpdateParColour(Self, Line, LineType);
-end;
-
 procedure TfrmDebug.Pause;
 begin
   if UIStatus = duiTest then Exit;
diff --git a/windows/src/developer/TIKE/child/UfrmKeymanWizard.pas b/windows/src/developer/TIKE/child/UfrmKeymanWizard.pas
index c8e4d2789e..73911bb0fa 100644
--- a/windows/src/developer/TIKE/child/UfrmKeymanWizard.pas
+++ b/windows/src/developer/TIKE/child/UfrmKeymanWizard.pas
@@ -437,6 +437,8 @@ type
     procedure TouchLayoutModified(Sender: TObject);
     procedure FocusTabTouchLayout;
 
+    procedure EditorBreakpointClicked(Sender: TObject; ALine: Integer);
+
     procedure FillFeatureGrid;
     procedure CheckParserSourceMove(Changed: Boolean);
     procedure ToggleWinLanguagesRow(Y: Integer);
@@ -488,7 +490,9 @@ type
     procedure StopDebugging;
     function PrepareForBuild(var DebugReset: Boolean): Boolean;   // I4504
 
-    procedure UpdateParColour(Sender: TObject; ALine: Integer; ALineType: TParColourLineType);
+    procedure DebugSetBreakpoint(Sender: TObject; ALine: Integer);
+    procedure DebugClearBreakpoint(Sender: TObject; ALine: Integer);
+    procedure DebugUpdateExecutionPoint(Sender: TObject; ALine: Integer);
 
     function HasSubfilename(const Filename: string): Boolean; override;   // I4081
 
@@ -626,6 +630,7 @@ begin
   frameSource.EditorFormat := efKMN;
   frameSource.Visible := True;
   frameSource.OnChanged := SourceChanged;
+  frameSource.OnBreakpointClicked := EditorBreakpointClicked;
   frameSource.TextFileFormat := FTextFileFormat;
 
   pages.ActivePage := pageDetails;
@@ -702,6 +707,13 @@ end;
 { General Functions                                                           }
 {-----------------------------------------------------------------------------}
 
+procedure TfrmKeymanWizard.EditorBreakpointClicked(Sender: TObject;
+  ALine: Integer);
+begin
+  if Assigned(FDebugForm) then
+    FDebugForm.ToggleBreakpoint(ALine);
+end;
+
 procedure TfrmKeymanWizard.EnableControls;
 begin
   BitmapEnableControls;
@@ -1478,11 +1490,6 @@ begin
   tmrUpdateCharacterMap.Enabled := True;
 end;
 
-procedure TfrmKeymanWizard.UpdateParColour(Sender: TObject; ALine: Integer; ALineType: TParColourLineType);
-begin
-  frameSource.UpdateParColour(ALine, ALineType);
-end;
-
 procedure TfrmKeymanWizard.SelectVKey(VKey: Integer);
 begin
   kbdLayout.SelectedKey := kbdLayout.Keys.ItemsByUSVK[VKey];
@@ -1942,6 +1949,22 @@ begin
   frmKeymanDeveloper.cbTextFileFormat.ItemIndex := Ord(TextFileFormat);
 end;
 
+procedure TfrmKeymanWizard.DebugClearBreakpoint(Sender: TObject;
+  ALine: Integer);
+begin
+  frameSource.DebugClearBreakpoint(ALine);
+end;
+
+procedure TfrmKeymanWizard.DebugSetBreakpoint(Sender: TObject; ALine: Integer);
+begin
+  frameSource.DebugSetBreakpoint(ALine);
+end;
+
+procedure TfrmKeymanWizard.DebugUpdateExecutionPoint(Sender: TObject; ALine: Integer);
+begin
+  frameSource.DebugUpdateExecutionPoint(ALine);
+end;
+
 procedure TfrmKeymanWizard.DoFocus(control: TWinControl);
 begin
   if control.Enabled and control.Visible and control.Showing and control.CanFocus then
@@ -2835,7 +2858,9 @@ begin
   FDebugForm.BorderStyle := bsNone;
   FDebugForm.Parent := panDebugWindowHost;
   FDebugForm.Align := alClient;
-  FDebugForm.OnUpdateParColour := UpdateParColour;
+  FDebugForm.OnSetBreakpoint := DebugSetBreakpoint;
+  FDebugForm.OnClearBreakpoint := DebugClearBreakpoint;
+  FDebugForm.OnUpdateExecutionPoint := DebugUpdateExecutionPoint;
   FDebugForm.Visible := True;
 
 
diff --git a/windows/src/developer/TIKE/main/UframeTextEditor.pas b/windows/src/developer/TIKE/main/UframeTextEditor.pas
index c875a3fd32..6517f4d004 100644
--- a/windows/src/developer/TIKE/main/UframeTextEditor.pas
+++ b/windows/src/developer/TIKE/main/UframeTextEditor.pas
@@ -32,7 +32,7 @@ uses
   UserMessages;
 
 type
-  TParColourLineType = (pcltNone, pcltBreakpoint, pcltExecutionPoint, pcltError);
+  TEditorBreakpointClickedEvent = procedure(Sender: TObject; ALine: Integer) of object;
 
   TframeTextEditor = class(TTIKEForm, IKMDEditActions, IKMDSearchActions, IKMDTextEditorActions)
     lstImages: TMenuImgList;
@@ -59,6 +59,7 @@ type
 
     cef: TframeCEFHost;
     FFilename: string;
+    FOnBreakpointClicked: TEditorBreakpointClickedEvent;
 
     procedure RefreshOptions;
     function GetText: WideString;
@@ -91,9 +92,11 @@ type
     procedure LoadFileInBrowser(const AData: string);
     procedure UpdateInsertState(const AMode: string);
     procedure ExecuteCommand(const command: string; const parameters: TJSONValue = nil);
+    procedure ExecuteLineCommand(ALine: Integer; const command: string);
     procedure UpdateToken(command: string);
     procedure SetCursorPosition(AColumn, ARow: Integer);
     procedure cefLoadEnd(Sender: TObject);
+    procedure DoBreakpointClicked(const line: string);
 
   protected
     function GetHelpTopic: string; override;
@@ -136,7 +139,11 @@ type
 
   public
     { Public declarations }
-    procedure UpdateParColour(par: Integer; LineType: TParColourLineType);
+    procedure DebugSetBreakpoint(ALine: Integer);
+    procedure DebugClearBreakpoint(ALine: Integer);
+    procedure DebugUpdateExecutionPoint(ALine: Integer);
+    property OnBreakpointClicked: TEditorBreakpointClickedEvent read FOnBreakpointClicked write FOnBreakpointClicked;
+
     procedure SetFocus; override;
 
     procedure FindError(ln: Integer);
@@ -170,6 +177,7 @@ implementation
 uses
   System.TypInfo,
   Vcl.Clipbrd,
+
   Keyman.Developer.System.HelpTopics,
 
   dmActionsMain,
@@ -785,6 +793,21 @@ begin
   cef.cef.ClipboardCut;
 end;
 
+procedure TframeTextEditor.DebugClearBreakpoint(ALine: Integer);
+begin
+  ExecuteLineCommand(ALine, 'clearBreakpoint');
+end;
+
+procedure TframeTextEditor.DebugSetBreakpoint(ALine: Integer);
+begin
+  ExecuteLineCommand(ALine, 'setBreakpoint');
+end;
+
+procedure TframeTextEditor.DebugUpdateExecutionPoint(ALine: Integer);
+begin
+  ExecuteLineCommand(ALine, 'updateExecutionPoint');
+end;
+
 procedure TframeTextEditor.PasteFromClipboard;
 begin
   cef.cef.ClipboardPaste;
@@ -832,28 +855,32 @@ begin
   end;
 end;
 
-procedure TframeTextEditor.FindError(ln: Integer);
+procedure TframeTextEditor.ExecuteLineCommand(ALine: Integer;
+  const command: string);
 var
   v: TJSONNumber;
+begin
+  v := TJSONNumber.Create(ALine);
+  try
+    ExecuteCommand(command, v);
+  finally
+    v.Free;
+  end;
+end;
+
+procedure TframeTextEditor.FindError(ln: Integer);
 begin
   ClearError;
   if (ln <= 0) then Exit;
 
-  v := TJSONNumber.Create(ln);
-  try
-    ExecuteCommand('highlightError', v);
-    SetSelectedRow(ln);
-  finally
-    v.Free;
-  end;
+  ExecuteLineCommand(ln, 'highlightError');
+  SetSelectedRow(ln);
 end;
 
 function TframeTextEditor.OffsetToLine(Offset: Integer): Integer;   // I4083
 var
   line: Integer;
 begin
-  Result := 0;
-
   with TStringList.Create do
   try
     Text := Self.GetText;
@@ -879,40 +906,49 @@ end;
 procedure TframeTextEditor.FireCommand(const commands: TStringList);
 var
   i: Integer;
-  command: string;
+  command0, command: string;
+  commandParams: TArray<string>;
 begin
   i := 0;
   while i < commands.Count do
   begin
-    command := commands[i];
+    command0 := commands[i];
+    commandParams := command0.Split([',']);
+    command := commandParams[0];
     if command = 'modified' then Changed   // I3948
-
     else if command = 'undo-disable' then FCanUndo := False
     else if command = 'undo-enable' then FCanUndo := True
     else if command = 'redo-disable' then FCanRedo := False
     else if command = 'redo-enable' then FCanRedo := True
     else if command = 'has-selection' then FHasSelection := True
     else if command = 'no-selection' then FHasSelection := False
-    else if command.StartsWith('insert-mode,') then
+    else if command = 'breakpoint-clicked' then DoBreakpointClicked(commandParams[1])
+    else if command0.StartsWith('insert-mode,') then
     begin
-      UpdateInsertState(command.Substring('insert-mode,'.Length));
+      UpdateInsertState(command0.Substring('insert-mode,'.Length));
     end
-    else if command.StartsWith('location,') then
+    else if command0.StartsWith('location,') then
     begin
-      UpdateState(command.Substring('location,'.Length));
+      UpdateState(command0.Substring('location,'.Length));
     end
-    else if command.StartsWith('token,') then
+    else if command0.StartsWith('token,') then
     begin
-      UpdateToken(command.Substring('token,'.Length));
+      UpdateToken(command0.Substring('token,'.Length));
     end
     else ShowMessage('keyman:'+commands.Text);
     Inc(i);
   end;
 end;
 
+procedure TframeTextEditor.DoBreakpointClicked(const line: string);
+begin
+  if Assigned(FOnBreakpointClicked) then
+    FOnBreakpointClicked(Self, StrToInt(line));
+end;
+
 procedure TframeTextEditor.UpdateToken(command: string);
 var
-  n, col: Integer;
+  col: Integer;
   line: string;
   x, tx: Integer;
   token, prevtoken: WideString;
@@ -968,23 +1004,6 @@ begin
   end;
 end;
 
-procedure TframeTextEditor.UpdateParColour(par: Integer; LineType: TParColourLineType);
-var
-  j: TJSONObject;
-begin
-  if par < 0 then Exit;
-  j := TJSONObject.Create;
-  try
-    j.AddPair('row', TJSONNumber.Create(par));
-    if LineType <> pcltNone then
-      j.AddPair('style', TJSONString.Create(GetEnumName(TypeInfo(TParColourLineType), Ord(LineType))));
-    ExecuteCommand('setRowColor', j);
-  finally
-    j.Free;
-  end;
-end;
-
-
 function TframeTextEditor.GetHelpTopic: string;
 begin
   if FEditorFormat <> efKMN then
diff --git a/windows/src/developer/TIKE/xml/app/editor/editor.css b/windows/src/developer/TIKE/xml/app/editor/editor.css
index 75e91847a3..0b5916b2dc 100644
--- a/windows/src/developer/TIKE/xml/app/editor/editor.css
+++ b/windows/src/developer/TIKE/xml/app/editor/editor.css
@@ -11,27 +11,14 @@ html, body {
   left: 0;
 }
 
-.ace_marker-layer .km_error,
-.ace_marker-layer .km_pcltBreakpoint,
-.ace_marker-layer .km_pcltExecutionPoint,
-.ace_marker-layer .km_pcltError {
-    position: absolute;
-    z-index: 3;
-}
-
-/*.ace-chrome*/ .ace_marker-layer .km_error {
+.km_error {
   background: rgb(255, 128, 128);
 }
 
-/*.ace-chrome*/ .ace_marker-layer .km_pcltBreakpoint {
-  background-color: forestgreen;
+.km_breakpoint {
+    background: url("data:image/svg+xml;charset=utf-8,%3Csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 16 16'%3E%3Cdefs%3E%3Cstyle%3E.icon-canvas-transparent,.icon-vs-out{fill:%23f6f6f6}.icon-canvas-transparent{opacity:0}.icon-vs-red{fill:%23e51400}%3C/style%3E%3C/defs%3E%3Ctitle%3Ebreakpoint%3C/title%3E%3Cpath class='icon-canvas-transparent' d='M16 0v16H0V0z' id='canvas'/%3E%3Cpath class='icon-vs-red' d='M11.789 8A3.789 3.789 0 1 1 8 4.211 3.788 3.788 0 0 1 11.789 8z' id='iconBg'/%3E%3C/svg%3E") 50% no-repeat
 }
 
-/*.ace-chrome*/ .ace_marker-layer .km_pcltExecutionPoint {
+.km_executionPoint {
     background-color: deepskyblue;
 }
-
-/*.ace-chrome*/ .ace_marker-layer .km_pcltError {
-    background: rgb(255, 128, 128);
-}
-                
\ No newline at end of file
diff --git a/windows/src/developer/TIKE/xml/app/editor/editor.js b/windows/src/developer/TIKE/xml/app/editor/editor.js
index 56164ff22a..52a5efdb01 100644
--- a/windows/src/developer/TIKE/xml/app/editor/editor.js
+++ b/windows/src/developer/TIKE/xml/app/editor/editor.js
@@ -1,3 +1,11 @@
+/*
+ * Editor using monaco
+ * 
+ * Helpful references:
+ * https://microsoft.github.io/monaco-editor/api/index.html
+ * https://blog.expo.io/building-a-code-editor-with-monaco-f84b3a06deaf 
+ */
+
 window.editorGlobalContext = {
   loading: false
 };
@@ -5,7 +13,8 @@ window.editorGlobalContext = {
 (function(context) {
   var editor = null;
   var errorRange = null;
-  var ranges = [];
+  var executionPoint = [];
+  var breakpoints = [];
   let params = (new URL(location)).searchParams;
   let filename = params.get('filename');
   let mode = params.get('mode');
@@ -13,103 +22,153 @@ window.editorGlobalContext = {
   if(!mode) {
     mode = 'keyman';
   }
-  
+
+
+  /**
+    Initialize the editor
+  */
+
+  require.config({ paths: { 'vs': '../lib/monaco/min/vs' } });
+  require(['vs/editor/editor.main'], function () {
+    editor = monaco.editor.create(document.getElementById('editor'), {
+      language: mode,
+      minimap: {
+        enabled: false
+      },
+      glyphMargin: true,
+      disableMonospaceOptimizations: true
+    });
+
+    $.get("/app/source/file",
+      {
+        Filename: filename
+      },
+      function (response) {
+        context.loading = true;
+        editor.setValue(response);
+        context.loading = false;
+      },
+      "text"
+    );
+
+    const model = editor.getModel();
+    model.onDidChangeContent(() => {
+      // Even when loading, we post back the data to the backend so we have an original version
+      $.post("/app/source/file", {
+        Filename: filename,
+        Data: model.getValue()
+        // delta.start, delta.end, delta.lines, delta.action
+      });
+      if (!context.loading) {
+        context.highlightError(); // clear the selected error
+        command('modified');
+        updateState();
+      }
+    });
+
+    editor.onDidChangeCursorPosition(updateState);
+    editor.onDidChangeCursorSelection(updateState);
+    editor.onMouseDown(e => {
+      if (e.target.type !== monaco.editor.MouseTargetType.GUTTER_GLYPH_MARGIN) {
+        return;
+      }
+      command('breakpoint-clicked,'+(e.target.position.lineNumber-1));
+    });
+  });
+
   /* Search and replace interfaces */
   
-  context.searchFind = function() {  
-    editor.commands.byName.find.exec(editor);
+  context.searchFind = function () {
+    editor.trigger('', 'actions.find');
   };
 
   context.searchFindNext = function() {  
-    editor.commands.byName.selectOrFindNext.exec(editor);
+    editor.trigger('', 'editor.action.nextMatchFindAction');
   };
 
   context.searchReplace = function() {  
-    editor.commands.byName.replace.exec(editor);
+    editor.trigger('', 'editor.action.startFindReplaceAction');
   };
   
   /* Edit command interfaces */
 
   context.editUndo = function() {
-    editor.undo();
+    editor.model.undo();
   };
 
   context.editRedo = function() {
-    editor.redo();
+    editor.model.redo();
   };
   
   context.editSelectAll = function() {
-    editor.selectAll();
+    editor.setSelection(editor.model.getFullModelRange());
   };
 
   /* Row selection */
 
   context.moveCursor = function (o) {
-    editor.moveCursorTo(o.row, o.column);
-    editor.selection.clearSelection();
-    editor.renderer.scrollCursorIntoView();
+    editor.setPosition({ column: o.column + 1, lineNumber: o.row + 1 });
+    editor.revealPositionInCenterIfOutsideViewport(editor.getPosition(), monaco.editor.ScrollType.Smooth);
   };
   
+  /* Debug interactions */
+  
+  context.setBreakpoint = function (row) {
+    if (!breakpoints[row]) {
+      breakpoints[row] = editor.deltaDecorations(
+        [],
+        [{ range: new monaco.Range(row + 1, 1, row + 1, 1), options: { isWholeLine: true, glyphMarginClassName: 'km_breakpoint' } }]
+      );
+    }
+  };
+  
+  context.clearBreakpoint = function (row) {
+    if (breakpoints[row]) {
+      editor.deltaDecorations(breakpoints[row], []);
+      breakpoints[row] = null;
+    }
+  };
+
+  context.updateExecutionPoint = function (row) {
+    executionPoint = editor.deltaDecorations(
+      executionPoint,
+      row >= 0 ? [{ range: new monaco.Range(row + 1, 1, row + 1, 1), options: { isWholeLine: true, linesDecorationsClassName: 'km_executionPoint' } }] : []
+    );
+    context.moveCursor({ row: row, column: 0 });
+  };
+
   /* Error highlighting */
-  
-  context.setRowColor = function(o) {
-    if (o.style) {
-      var r = new ace.Range(o.row, 0, o.row, Infinity);
-      r.row = o.row;
-      r.id = editor.session.addMarker(r, 'km_'+o.style, "fullLine", false);
-      ranges.push(r);
-    } else {
-      ranges = ranges.filter(function (v) {
-        if (v.row !== o.row) {
-          return true;
-        }
-        editor.session.removeMarker(v.id);
-        return false;
-      });
+
+  context.highlightError = function (row) {
+    if (errorRange) {
+      editor.deltaDecorations(errorRange, []);
+      errorRange = null;
     }
-    editor.moveCursorTo(o.row, 0);
-    editor.selection.clearSelection();
-    editor.renderer.scrollCursorIntoView();
-  };
-  
-  context.highlightError = function(row) {
-    if(errorRange) {
-      editor.session.removeMarker(errorRange.id);
-    }
-    if(typeof row == 'number') {
-      errorRange = new ace.Range(row, 0, row, Infinity);
-      errorRange.id = editor.session.addMarker(errorRange, 'km_error', "fullLine", false);
+    if (typeof row == 'number') {
+      errorRange = editor.deltaDecorations([], [{ range: new monaco.Range(row + 1, 1, row + 1, 1), options: { isWholeLine: true, linesDecorationsClassName: 'km_error', className: 'km_error' } }]);
     }
   };
 
   context.replaceSelection = function (o) {
-    let originalRange = new ace.Range(o.top, o.left, o.bottom, o.right);
-    let end = editor.session.doc.replace(originalRange, o.newText);
-
-    let newRange = new ace.Range(o.top, o.left, end.row, end.column);
-    editor.selection.setSelectionRange(newRange, false);
+    let r = new monaco.Range(o.top + 1, o.left + 1, o.bottom + 1, o.right + 1);
+    editor.setSelection(r);
+    editor.executeEdits("", [
+      { range: r, text: o.newText }
+    ]);
   };
   
   context.setText = function (text) {
-    let range = editor.session.selection.getRange();
+    let range = editor.getSelection();
     context.loading = true;
-    editor.session.setValue(text);
-    editor.session.selection.setSelectionRange(range);
-    context.loading = false;
-  };
-
-  context.setText = function (text) {
-    let range = editor.session.selection.getRange();
-    context.loading = true;
-    editor.session.setValue(text);
-    editor.session.selection.setSelectionRange(range);
+    editor.setValue(text);
+    editor.setSelection(range);
     context.loading = false;
   };
 
   /* Printing */
 
   context.print = function () {
-    require("ace/config").loadModule("ace/ext/static_highlight", function (m) {
+    /****require("ace/config").loadModule("ace/ext/static_highlight", function (m) {
       var result = m.renderSync(
         editor.getValue(), editor.session.getMode(), editor.renderer.theme
       );
@@ -129,7 +188,7 @@ window.editorGlobalContext = {
         }, 10);
       };
       document.body.appendChild(iframe);
-    });
+    });*/
   };
       
   /**
@@ -162,84 +221,38 @@ window.editorGlobalContext = {
   
   /**
   */
-  var updateState = function() {
-    command(editor.getSelectedText() == '' ? 'no-selection' : 'has-selection');
-    command(editor.session.getUndoManager().hasUndo() ? 'undo-enable' : 'undo-disable');
-    command(editor.session.getUndoManager().hasRedo() ? 'redo-enable' : 'redo-disable');
-    let r = editor.selection.getRange();
-    var n = editor.session.doc.getTextRange(editor.selection.getRange()).length;
-    if (!editor.selection.isBackwards()) n = -n;
-    command('location,' + r.start.row + ',' + r.start.column + ',' + r.end.row + ',' + r.end.column + ',' + n);
-    command('insert-mode,' + (editor.session.getOption('overwrite') ? 'Overwrite' : 'Insert'));
-//    command(editor.session.getUndoManager().isClean() ? 'modified' : 'not-modified');
-    var s = getTokenAtCursor();
-    if(s) {
-      command('token,'+s.column+','+encodeURIComponent(s.text));
+  var updateState = function () {
+    let s = editor.getSelection();
+    command(s.isEmpty() ? 'no-selection' : 'has-selection');
+    command(editor.model.canUndo() ? 'undo-enable' : 'undo-disable');
+    command(editor.model.canRedo() ? 'redo-enable' : 'redo-disable');
+
+    var n = editor.model.getValueInRange(s).length;
+    if (editor.getSelection().getDirection() == monaco.SelectionDirection.LTR) n = -n;
+    command('location,' + (s.startLineNumber-1) + ',' + (s.startColumn-1) + ',' + (s.endLineNumber-1) + ',' + (s.endColumn-1) + ',' + n);
+    //command('insert-mode,' + (editor.session.getOption('overwrite') ? 'Overwrite' : 'Insert'));
+    var token = getTokenAtCursor();
+    if (token) {
+      command('token,' + token.column + ',' + encodeURIComponent(token.text));
     }
   };
-  
-  var getTokenAtCursor = function() {
-    var txt = editor.getSelectedText();
-    if(txt != '') {
+
+  var getTokenAtCursor = function () {
+    var txt = editor.model.getValueInRange(editor.getSelection());
+    if (txt != '') {
       // We'll always return the first 100 characters of the selection and not 
       // do any manipulation here.
-      return {column:null,text:txt.substr(0, 99)};
+      return { column: null, text: txt.substr(0, 99) };
     }
-    
-    if(mode == 'keyman') {
+
+    if (mode == 'keyman') {
       // Get the token under the cursor
-      var c = editor.session.selection.getCursor();
-      var line = editor.session.getLine(c.row);
-      return {column:c.column, text:line};
+      var c = editor.getSelection();
+      var line = editor.model.getLineContent(c.positionLineNumber);
+      return { column: c.positionColumn-1, text: line };
     } else {
       // Get the character under the cursor
       return null;
     }
   };
-  
-  /**
-    Initialize the editor
-  */
-  $(function initialize() {
-    editor = ace.edit("editor");
-
-    // Remove Alt+ key bindings which may conflict with environment shortcuts, e.g. Alt+E, function keys
-
-    var reAltKeyBindings = /(^alt-[a-z0-9]|f[0-9]+)$/;
-    for (var key in editor.keyBinding.$defaultHandler.commandKeyBinding) {
-      if (key.match(reAltKeyBindings)) {
-        delete editor.keyBinding.$defaultHandler.commandKeyBinding[key];
-      }
-    }
-
-    editor.setTheme("ace/theme/xcode");
-    
-    editor.session.selection.on('changeCursor', updateState);    
-    editor.session.on('changeOverwrite', updateState);
-    editor.session.selection.on('changeSelection', updateState);
-    
-    editor.session.on('change', function (delta) {
-      // Even when loading, we post back the data to the backend so we have an original version
-      $.post("/app/source/file", {
-        Filename: filename,
-        Data: editor.session.getValue()
-        // delta.start, delta.end, delta.lines, delta.action
-      });
-      if (!context.loading) {
-        context.highlightError(); // clear the selected error
-        command('modified');
-        updateState();
-      }
-    });
-    // Start reading the source file
-    $.get("/app/source/file", { 
-      Filename: filename
-    }, function (response) {
-      context.loading = true;
-      editor.session.setValue(response);
-      editor.session.setMode("ace/mode/"+mode);
-      context.loading = false;
-    }, 
-    "text"); 
-  });
 })(window.editorGlobalContext);
\ No newline at end of file
diff --git a/windows/src/developer/TIKE/xml/app/editor/index.html b/windows/src/developer/TIKE/xml/app/editor/index.html
index eb4ae31a05..939e578d1b 100644
--- a/windows/src/developer/TIKE/xml/app/editor/index.html
+++ b/windows/src/developer/TIKE/xml/app/editor/index.html
@@ -1,4 +1,4 @@
-<!DOCTYPE html>
+<!DOCTYPE html>
 <html>
   <head>
     <meta charset='utf-8'>
@@ -15,11 +15,12 @@
  
     <link rel="stylesheet" type='text/css' href='editor.css' />
     
-    <script src="../lib/ace/ace.js" charset="utf-8"></script>
     <script src="../lib/jquery/jquery-1.10.2.js"></script>
-    <script src="editor.js"></script>
   </head>
   <body>
     <div id="editor"></div>
+
+    <script src="../lib/monaco/min/vs/loader.js"></script>
+    <script src="editor.js"></script>
   </body>
 </html>