Fixes issue rendering when node is collapsed and text has new lines

It happens when text doesn't exceed the maxwidth and we have
multiple lines because the new lines

Author: netonjm

TestApps/Samples/Samples/TreeViewEvents.cs

@@ -48,7 +48,7 @@ public TreeViewEvents ()
 			tree.Columns.Add (col);
 
 			var node = store.AddNode ().SetValue (nodeField, new TextNode ("Root 1"));
-			var child = node.AddChild ().SetValue (nodeField, new TextNode ("Very long text. Very long text. Very long text. Very long text. Very long text. Very long text. Very long text. Very long text."));
+			var child = node.AddChild ().SetValue (nodeField, new TextNode ($"Very long text with NewLines. {Environment.NewLine} Very long text with NewLines.{Environment.NewLine} Very long text. Very long text. Very long text. Very long text."));
 			node = store.AddNode ().SetValue (nodeField, new TextNode ("Root 2"));
 			child = node.AddChild ().SetValue (nodeField, new TextNode ("Short text. Short text. Short text."));
 			child.AddChild ().SetValue (nodeField, new TextNode ("Very long text. Very long text. Very long text. Very long text. Very long text. Very long text. Very long text. Very long text."));
@@ -100,6 +100,17 @@ class ViewStatus
 		TextNode selectionRow;
 		bool dragging;
 
+		//defines the default height size based in the current font
+		//if will work if you use same font size in every row,
+		//if not, you'll need check in every OnGetRequiredSize
+		double defaultHeight;
+
+		public ExpandableTextCellView () 
+		{
+			var defaultLayout = new TextLayout() { Text = "A" };
+			defaultHeight = defaultLayout.GetSize().Height;
+		}
+
 		ViewStatus GetViewStatus (TextNode node)
 		{
 			ViewStatus status;
@@ -125,9 +136,15 @@ protected override Size OnGetRequiredSize ()
 				textSize = layout.GetSize ();
 			}
 
-			status.LastCalculatedHeight = textSize.Height;
+			//in cases when there are multiple lines and they don't execeed the max width we need to care height include the expand
+			double height = textSize.Height;
+			if (!status.Expanded && textSize.Height > defaultHeight) {
+				height = defaultHeight;
+			}
+
+			status.LastCalculatedHeight = height;
 
-			return new Size (30, textSize.Height);
+			return new Size (30, height);
 		}
 
  		protected override void OnDraw (Context ctx, Rectangle cellArea)
@@ -147,9 +164,16 @@ protected override void OnDraw (Context ctx, Rectangle cellArea)
 				layout.SetBackground (Colors.LightBlue, Math.Min (selectionStart, selectionEnd), Math.Abs (selectionEnd - selectionStart));
 
 			// Text doesn't fit. We need to render the expand icon
+			if (textSize.Width > cellArea.Width || textSize.Height > cellArea.Height) {
+
+				if (textSize.Width > cellArea.Width || textSize.Height > cellArea.Height) {
+					layout.Width = Math.Max(1, cellArea.Width - addImage.Width - MoreLinkSpacing);
+
+					if (textSize.Height > cellArea.Height) {
+						layout.Height = cellArea.Height;
+					}
+				}
 
-			if (textSize.Width > cellArea.Width) {
-				layout.Width = Math.Max (1, cellArea.Width - addImage.Width - MoreLinkSpacing);
 				if (!status.Expanded)
 					layout.Trimming = TextTrimming.WordElipsis;
 				else