replace uses of important literal with an unique string const

src/u_common.pas

@@ -337,6 +337,10 @@ var
   // terminal used under posix
   consoleProgram: string;
 
+const
+  // used as page caption and filename when a doc has never been saved
+  newdocPageCaption = '<new document>';
+
 
 implementation
 

src/u_editor.pas

@@ -515,7 +515,7 @@ end;
 procedure TEditorWidget.docFocused(document: TDexedMemo);
 begin
   if fDoc.isNotNil and pageControl.currentPage.isNotNil and
-    (pageControl.currentPage.Caption = '<new document>') then
+    (pageControl.currentPage.Caption = newdocPageCaption) then
       updatePageCaption(pageControl.currentPage);
   if document = fDoc then
     exit;
@@ -652,7 +652,7 @@ end;
 procedure TEditorWidget.pageBtnAddCLick(Sender: TObject);
 begin
   TDexedMemo.Create(nil);
-  pageControl.currentPage.Caption:='<new document>';
+  pageControl.currentPage.Caption := newdocPageCaption;
 end;
 
 procedure TEditorWidget.setDetectModuleName(value: boolean);
@@ -675,7 +675,7 @@ begin
   fDoc.hideCallTips;
   fDoc.hideDDocs;
   if (pageControl.currentPage.Caption = '') or
-    (pageControl.currentPage.Caption ='<new document>') then
+    (pageControl.currentPage.Caption = newdocPageCaption) then
   begin
     fKeyChanged := true;
     beginDelayedUpdate;
@@ -842,7 +842,7 @@ end;
 
 procedure TEditorWidget.updatePageCaption(page: TDexedPage);
 var
-  txt: string = '<new document>';
+  txt: string = newdocPageCaption;
   dc1: TDexedMemo = nil;
   dc2: TDexedMemo = nil;
 begin

src/u_gdb.pas

@@ -1525,7 +1525,7 @@ begin
   fDoc := document;
   if fGdbState = gsNone then
     updateDebugeeOptionsEditor;
-  if (fDoc.fileName <> '<new document>') then
+  if (fDoc.fileName <> newdocPageCaption) then
   begin
     fSynchronizingBreakpoints:= true;
     if fSynchronizedDocuments.IndexOf(document.fileName) = -1 then

src/u_synmemo.pas

@@ -1147,7 +1147,7 @@ begin
   Highlighter := fD2Highlighter;
 
   fTempFileName := GetTempDir(false) + 'temp_' + uniqueObjStr(self) + '.d';
-  fFilename := '<new document>';
+  fFilename := newdocPageCaption;
   fModified := false;
   TextBuffer.AddNotifyHandler(senrUndoRedoAdded, @changeNotify);
 
@@ -3138,7 +3138,7 @@ begin
     if fFilename.length > 0 then
       result := fFilename.extractFileName
     else
-      result := '<new document>';
+      result := newdocPageCaption;
   end;
 end;
 
@@ -3437,7 +3437,7 @@ begin
   if fDiffDialogWillClose or fDisableFileDateCheck then
     exit;
   if fFilename.isNotEmpty and not fFilename.fileExists and
-    (fFilename <> '<new document>') then
+    (fFilename <> newdocPageCaption) then
   begin
     // cant use a dialog: dialog closed -> doc focused -> warn again, etc
     getMessageDisplay.message(fFilename + ' does not exist anymore', self, amcEdit, amkWarn);