Mono.TextEditor.TextEditorData.OpenUndoGroup C# (CSharp) Method

		public IDisposable OpenUndoGroup()
		{
			return Document.OpenUndoGroup ();
		}

		public static void Left (TextEditorData data)
		{
			using (var undo = data.OpenUndoGroup ()) {
				if (Platform.IsMac && data.IsSomethingSelected && !data.Caret.PreserveSelection) {
					data.Caret.Offset = System.Math.Min (data.SelectionAnchor, data.Caret.Offset);
					data.ClearSelection ();
					return;
				}
				
				if (data.Caret.Column > DocumentLocation.MinColumn) {
					DocumentLine line = data.Document.GetLine (data.Caret.Line);
					if (data.Caret.Column > line.Length + 1) {
						if (data.Caret.AllowCaretBehindLineEnd) {
							data.Caret.Column--;
						} else {
							data.Caret.Column = line.Length + 1;
						}
					} else {
						int offset = data.Caret.Offset - 1;
						foreach (var folding in data.Document.GetFoldingsFromOffset (offset).Where (f => f.IsFolded && f.Offset < offset)) {
							offset = System.Math.Min (offset, folding.Offset);
						}
						data.Caret.Offset = offset;
					}
				} else if (data.Caret.Line > DocumentLocation.MinLine) {
					DocumentLine prevLine = data.Document.GetLine (data.Caret.Line - 1);
					var nextLocation = new DocumentLocation (data.Caret.Line - 1, prevLine.Length + 1);
					if (data.HasIndentationTracker && data.Options.IndentStyle == IndentStyle.Virtual && nextLocation.Column == DocumentLocation.MinColumn)
						nextLocation = new DocumentLocation (data.Caret.Line - 1, data.GetVirtualIndentationColumn (nextLocation));
					data.Caret.Location = nextLocation;
				}
			}
		}