diff --git a/src/Axis.vala b/src/Axis.vala
index 6341aa1..938fb02 100644
--- a/src/Axis.vala
+++ b/src/Axis.vala
@@ -5,11 +5,11 @@ namespace CairoChart {
 	 */
 	public class Axis {
 
-		Chart chart;
-		string _format = "%.2Lf";
-		string _date_format = "%Y.%m.%d";
-		string _time_format = "%H:%M:%S";
-		int _dsec_signs = 2; // 2 signs = centiseconds
+		protected Chart chart;
+		protected string _format = "%.2Lf";
+		protected string _date_format = "%Y.%m.%d";
+		protected string _time_format = "%H:%M:%S";
+		protected int _dsec_signs = 2; // 2 signs = centiseconds
 
 		/**
 		 * ``Axis`` title.
diff --git a/src/Chart.vala b/src/Chart.vala
index fce64b4..6c6fe24 100644
--- a/src/Chart.vala
+++ b/src/Chart.vala
@@ -309,7 +309,6 @@ namespace CairoChart {
 
 		protected virtual void eval_plarea () {
 			plarea = evarea.copy();
-			legend.show = false;
 			if (legend.show)
 				switch(legend.position) {
 				case Legend.Position.TOP: plarea.y0 += legend.spacing; break;
diff --git a/src/Cursor.vala b/src/Cursor.vala
index eac3278..7ffbcb4 100644
--- a/src/Cursor.vala
+++ b/src/Cursor.vala
@@ -1,18 +1,35 @@
 namespace CairoChart {
 
+	/**
+	 * {@link Chart} cursors.
+	 */
 	public class Cursors {
 
+		protected Chart chart;
 		protected List<Point?> list = new List<Point?> ();
 		protected Point active_cursor = Point(); // { get; protected set; default = Point128 (); }
 		protected bool is_cursor_active = false; // { get; protected set; default = false; }
-		public Cursors.Style cursor_style = Cursors.Style();
-		public Cursors.CursorCrossings[] crossings = {};
-		Chart chart;
 
+		/**
+		 *
+		 */
+		public Cursors.Style cursor_style = Cursors.Style();
+
+		/**
+		 *
+		 */
+		public Cursors.CursorCrossings[] crossings = {};
+
+		/**
+		 *
+		 */
 		public Cursors (Chart chart) {
 			this.chart = chart;
 		}
 
+		/**
+		 *
+		 */
 		public Cursors copy () {
 			var c = new Cursors (chart);
 			c.list = list.copy();
@@ -23,17 +40,36 @@ namespace CairoChart {
 			return c;
 		}
 
+		/**
+		 *
+		 */
 		protected enum Orientation {
-			VERTICAL = 0,  // default
+			VERTICAL = 0,
 			HORIZONTAL
 		}
 
+		/**
+		 *
+		 */
 		protected struct Style {
-
+			/**
+			 *
+			 */
 			public Orientation orientation;
+
+			/**
+			 *
+			 */
 			public double select_distance;
+
+			/**
+			 *
+			 */
 			public LineStyle line_style;
 
+			/**
+			 *
+			 */
 			public Style () {
 				orientation = Orientation.VERTICAL;
 				select_distance = 32;
diff --git a/src/Legend.vala b/src/Legend.vala
index 018f654..d30fb32 100644
--- a/src/Legend.vala
+++ b/src/Legend.vala
@@ -5,8 +5,8 @@ namespace CairoChart {
 	 */
 	public class Legend {
 
-		Chart chart;
-		double [] max_font_heights;
+		protected Chart chart;
+		protected double [] max_font_heights;
 
 		/**
 		 * ``Legend`` position.
@@ -158,12 +158,14 @@ namespace CairoChart {
 			var leg_height_sum = 0.0;
 			var max_font_h = 0.0;
 
+			double [] mfh = max_font_heights;
+
 			// prepare
 			switch (process_type) {
 			case ProcessType.CALC:
 				width = 0;
 				height = 0;
-				max_font_heights = {};
+				mfh = {};
 				heights_idx = 0;
 				break;
 			case ProcessType.DRAW:
@@ -172,7 +174,6 @@ namespace CairoChart {
 			}
 
 			foreach (var s in chart.series) {
-
 				if (!s.zoom_show) continue;
 
 				// carry
@@ -184,7 +185,7 @@ namespace CairoChart {
 						leg_height_sum += max_font_h;
 						switch (process_type) {
 						case ProcessType.CALC:
-							max_font_heights += max_font_h;
+							mfh += max_font_h;
 							width = double.max(width, leg_width_sum);
 							break;
 						case ProcessType.DRAW:
@@ -200,7 +201,7 @@ namespace CairoChart {
 				switch (process_type) {
 				case ProcessType.DRAW:
 					var x = legend_x0 + leg_width_sum + (leg_width_sum == 0 ? 0 : s.title.font.hspacing);
-					var y = legend_y0 + leg_height_sum + max_font_heights[heights_idx] / 2 + s.title.height / 2;
+					var y = legend_y0 + leg_height_sum + mfh[heights_idx] / 2 + s.title.height / 2;
 
 					// series title
 					chart.ctx.move_to (x + line_length, y);
@@ -228,7 +229,7 @@ namespace CairoChart {
 				case Position.RIGHT:
 					switch (process_type) {
 					case ProcessType.CALC:
-						max_font_heights += s.title.height + (leg_height_sum != 0 ? s.title.font.vspacing : 0);
+						mfh += s.title.height + (leg_height_sum != 0 ? s.title.font.vspacing : 0);
 						width = double.max (width, s.title.width + line_length);
 						break;
 					case ProcessType.DRAW:
@@ -248,7 +249,7 @@ namespace CairoChart {
 					leg_height_sum += max_font_h;
 					switch (process_type) {
 						case ProcessType.CALC:
-							max_font_heights += max_font_h;
+							mfh += max_font_h;
 							width = double.max(width, leg_width_sum);
 							break;
 					}
@@ -267,6 +268,8 @@ namespace CairoChart {
 				}
 				break;
 			}
+
+			max_font_heights = mfh;
 		}
 	}
 }
diff --git a/src/Marker.vala b/src/Marker.vala
index d4c2382..4368d72 100644
--- a/src/Marker.vala
+++ b/src/Marker.vala
@@ -5,7 +5,7 @@ namespace CairoChart {
 	 */
 	public class Marker {
 
-		Chart chart;
+		protected Chart chart;
 
 		/**
 		 * ``Marker`` shape.
diff --git a/src/Place.vala b/src/Place.vala
index 809a011..ae1781c 100644
--- a/src/Place.vala
+++ b/src/Place.vala
@@ -5,10 +5,10 @@ namespace CairoChart {
 	 */
 	public class Place {
 
-		double _x0 = 0;
-		double _x1 = 1;
-		double _y0 = 0;
-		double _y1 = 1;
+		protected double _x0 = 0;
+		protected double _x1 = 1;
+		protected double _y0 = 0;
+		protected double _y1 = 1;
 
 		/**
 		 * Zoomed Left bound.
diff --git a/src/Range.vala b/src/Range.vala
index 15cf989..6ed8bf9 100644
--- a/src/Range.vala
+++ b/src/Range.vala
@@ -5,8 +5,8 @@ namespace CairoChart {
 	 */
 	public class Range {
 
-		Float128 _min = 0;
-		Float128 _max = 1;
+		protected Float128 _min = 0;
+		protected Float128 _max = 1;
 
 		/**
 		 * Zoomed min bound.
diff --git a/src/Text.vala b/src/Text.vala
index 45c8574..4d19fcd 100644
--- a/src/Text.vala
+++ b/src/Text.vala
@@ -5,10 +5,10 @@ namespace CairoChart {
 	 */
 	public class Text {
 
-		Chart chart;
-		string _text;
-		Font _font;
-		Cairo.TextExtents? _ext;
+		protected Chart chart;
+		protected string _text;
+		protected Font _font;
+		protected Cairo.TextExtents? _ext;
 
 		/**
 		 * ``Text`` string.