Install FoldingElementGenerator first to ensure that fold markers are always drawn. Fixes InvalidOperationException in ICSharpCode.AvalonEdit.Rendering.TextView.BuildVisualLine.

git-svn-id: svn://svn.sharpdevelop.net/sharpdevelop/trunk@6229 1ccf3a8d-04fe-1044-b7c0-cef0b8235c61

src/Libraries/AvalonEdit/ICSharpCode.AvalonEdit/Folding/FoldingManager.cs

@@ -274,7 +274,8 @@ namespace ICSharpCode.AvalonEdit.Folding
 				margin = new FoldingMargin() { FoldingManager = this };
 				generator = new FoldingElementGenerator() { FoldingManager = this };
 				textArea.LeftMargins.Add(margin);
-				textArea.TextView.ElementGenerators.Add(generator);
+				// HACK: folding only works correctly when it has highest priority
+				textArea.TextView.ElementGenerators.Insert(0, generator);
 				textArea.Caret.PositionChanged += textArea_Caret_PositionChanged;
 			}