SynEdit: Add check for nil / Improve comments

git-svn-id: trunk@63450 -

components/synedit/synedit.pp

@@ -2692,8 +2692,14 @@ begin
 
     // When fixed FCaret, FBlockSelection, FTrimmedLinesView can move here
     FFoldedLinesView.UnLock;  // after ScanRanges, but before UpdateCaret
-   // must be last => May call MoveCaretToVisibleArea, which must only happen
-   // after unfold
+    (* FFoldedLinesView.UnLock
+       Any unfold (caused by caret move) will be done (deferred) in UnLock.
+       UpdateCaret may call MoveCaretToVisibleArea (which depends on what is folded)
+       Therefore UnLock must be called before UpdateCaret
+
+       Caret.Unlock must be done before UpdateCaret, because it sends the events
+         to FFoldedLinesView which triggers any unfold.
+    *)
 
     Dec(FPaintLock);
     if (FPaintLock = 0) and HandleAllocated then begin

components/synedit/syneditfoldedview.pp

@@ -24,7 +24,6 @@ of this file under either the MPL or the GPL.
 unit SynEditFoldedView;
 
 {$mode objfpc}{$H+}
-{$coperators on}
 {$IFDEF CPUPOWERPC} {$INLINE OFF} {$ENDIF} (* Workaround for bug 12576 (fpc) see bugs.freepascal.org/view.php?id=12576 *)
 
 {$IFOPT C+}
@@ -57,7 +56,12 @@ uses
 
 type
 
-  TFoldNodeClassification = (fncInvalid, fncHighlighter, fncHighlighterEx, fncBlockSelection);
+  TFoldNodeClassification = (
+    fncInvalid,
+    fncHighlighter,     // Fold provided by HL
+    fncHighlighterEx,   // Fold originally provided by HL, but no longer exists in HL (text edited)
+    fncBlockSelection
+  );
   TFoldNodeClassifications = set of TFoldNodeClassification;
 
   { TSynTextFoldAVLNodeData }
@@ -2968,7 +2972,8 @@ procedure TSynEditFoldProvider.SetLines(AValue: TSynEditStrings);
 begin
   if FLines = AValue then Exit;
   FLines := AValue;
-  FNestedFoldsList.Lines := FLines;
+  if FNestedFoldsList <> nil then
+    FNestedFoldsList.Lines := FLines;
 end;
 
 constructor TSynEditFoldProvider.Create;