As 2.x takes longer as planned, I added the SpeechbubbleContainer and StepLabelContainer (Enumerable label) to the 1.2 branch. This code was stored somewhere on my hard-drive, is still experimental.

Greenshot/Drawing/SpeechbubbleContainer.cs

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+/*
+ * Greenshot - a free and open source screenshot tool
+ * Copyright (C) 2007-2012  Thomas Braun, Jens Klingen, Robin Krom
+ * 
+ * For more information see: http://getgreenshot.org/
+ * The Greenshot project is hosted on Sourceforge: http://sourceforge.net/projects/greenshot/
+ * 
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 1 of the License, or
+ * (at your option) any later version.
+ * 
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+using Greenshot.Drawing.Fields;
+using Greenshot.Helpers;
+using Greenshot.Plugin;
+using Greenshot.Plugin.Drawing;
+using System;
+using System.Drawing;
+using System.Drawing.Drawing2D;
+using System.Windows.Forms;
+
+namespace Greenshot.Drawing {
+	/// <summary>
+	/// Description of SpeechbubbleContainer.
+	/// </summary>
+	[Serializable()]
+	public class SpeechbubbleContainer : TextContainer {
+		public SpeechbubbleContainer(Surface parent)
+			: base(parent) {
+		}
+
+		/// <summary>
+		/// We set our own field values
+		/// </summary>
+		protected override void InitializeFields() {
+			AddField(GetType(), FieldType.LINE_THICKNESS, 4);
+			AddField(GetType(), FieldType.LINE_COLOR, Color.Blue);
+			AddField(GetType(), FieldType.SHADOW, true);
+			AddField(GetType(), FieldType.FONT_ITALIC, false);
+			AddField(GetType(), FieldType.FONT_BOLD, false);
+			AddField(GetType(), FieldType.FILL_COLOR, Color.Transparent);
+			AddField(GetType(), FieldType.FONT_FAMILY, FontFamily.GenericSansSerif.Name);
+			AddField(GetType(), FieldType.FONT_SIZE, 20f);
+			AddField(GetType(), FieldType.TEXT_HORIZONTAL_ALIGNMENT, HorizontalAlignment.Center);
+			AddField(GetType(), FieldType.TEXT_VERTICAL_ALIGNMENT, VerticalAlignment.CENTER);
+		}
+
+		protected override void TargetGripperMove(int absX, int absY) {
+			base.TargetGripperMove(absX, absY);
+			Invalidate();
+		}
+		/// <summary>
+		/// Called from Surface (the _parent) when the drawing begins (mouse-down)
+		/// </summary>
+		/// <returns>true if the surface doesn't need to handle the event</returns>
+		public override bool HandleMouseDown(int mouseX, int mouseY) {
+			if (TargetGripper == null) {
+				InitTargetGripper(Color.Green, new Point(mouseX, mouseY));
+			}
+			return base.HandleMouseDown(mouseX, mouseY);
+		}
+
+		public override Rectangle DrawingBounds {
+			get {
+				return new Rectangle(0, 0, _parent.Width, _parent.Height);
+			}
+		}
+		public override void Draw(Graphics graphics, RenderMode renderMode) {
+			if (TargetGripper == null) {
+				return;
+			}
+			graphics.SmoothingMode = SmoothingMode.HighQuality;
+			graphics.InterpolationMode = InterpolationMode.HighQualityBicubic;
+			graphics.CompositingQuality = CompositingQuality.HighQuality;
+			graphics.PixelOffsetMode = PixelOffsetMode.None;
+
+			Color lineColor = GetFieldValueAsColor(FieldType.LINE_COLOR);
+			Color fillColor = GetFieldValueAsColor(FieldType.FILL_COLOR);
+			int lineThickness = GetFieldValueAsInt(FieldType.LINE_THICKNESS);
+
+			bool lineVisible = (lineThickness > 0 && Colors.IsVisible(lineColor));
+			Rectangle rect = GuiRectangle.GetGuiRectangle(Left, Top, Width, Height);
+
+			int tailAngle = 90 + (int)GeometryHelper.Angle2D(Left + (Width / 2), Top + (Height / 2), TargetGripper.Left, TargetGripper.Top);
+			int tailLength = GeometryHelper.Distance2D(Left + (Width / 2), Top + (Height / 2), TargetGripper.Left, TargetGripper.Top);
+			int tailWidth = (Math.Abs(Width) + Math.Abs(Height)) / 20;
+
+			GraphicsPath bubble = new GraphicsPath();
+			bubble.AddEllipse(0, 0, Math.Abs(rect.Width), Math.Abs(rect.Height));
+			bubble.CloseAllFigures();
+
+			GraphicsPath tail = new GraphicsPath();
+			tail.AddLine(-tailWidth, 0, tailWidth, 0);
+			tail.AddLine(tailWidth, 0, 0, -tailLength);
+			tail.CloseFigure();
+
+			GraphicsState state = graphics.Save();
+			// draw the tail border where the bubble is not visible
+			using (Region clipRegion = new Region(bubble)) {
+				clipRegion.Translate(Left, Top);
+				graphics.SetClip(clipRegion, CombineMode.Exclude);
+				graphics.TranslateTransform(Left + (Width / 2), Top + (Height / 2));
+				graphics.RotateTransform(tailAngle);
+				using (Pen pen = new Pen(lineColor, lineThickness)) {
+					graphics.DrawPath(pen, tail);
+				}
+			}
+			graphics.Restore(state);
+
+
+			if (Colors.IsVisible(fillColor)) {
+				//draw the bubbleshape
+				state = graphics.Save();
+				graphics.TranslateTransform(Left, Top);
+				using (Brush brush = new SolidBrush(fillColor)) {
+					graphics.FillPath(brush, bubble);
+				}
+				graphics.Restore(state);
+			}
+
+			if (lineVisible) {
+				//draw the bubble border
+				state = graphics.Save();
+				// Draw bubble where the Tail is not visible.
+				using (Region clipRegion = new Region(tail)) {
+					Matrix transformMatrix = new Matrix();
+					transformMatrix.Rotate(tailAngle);
+					clipRegion.Transform(transformMatrix);
+					clipRegion.Translate(Left + (Width / 2), Top + (Height / 2));
+					graphics.SetClip(clipRegion, CombineMode.Exclude);
+					graphics.TranslateTransform(Left, Top);
+					using (Pen pen = new Pen(lineColor, lineThickness)) {
+						graphics.DrawPath(pen, bubble);
+					}
+				}
+				graphics.Restore(state);
+			}
+
+			if (Colors.IsVisible(fillColor)) {
+				// Draw the tail border
+				state = graphics.Save();
+				graphics.TranslateTransform(Left + (Width / 2), Top + (Height / 2));
+				graphics.RotateTransform(tailAngle);
+				using (Brush brush = new SolidBrush(fillColor)) {
+					graphics.FillPath(brush, tail);
+				}
+				graphics.Restore(state);
+			}
+
+			// Draw the text
+			StringFormat format = new StringFormat();
+			format.Alignment = StringAlignment.Center;
+			format.LineAlignment = StringAlignment.Center;
+			DrawText(graphics, GuiRectangle.GetGuiRectangle(Left, Top, Width, Height), format);
+
+			// cleanup
+			bubble.Dispose();
+			tail.Dispose();
+		}
+
+		public override bool Contains(int x, int y) {
+			double xDistanceFromCenter = x - (Left + Width / 2);
+			double yDistanceFromCenter = y - (Top + Height / 2);
+			// ellipse: x^2/a^2 + y^2/b^2 = 1
+			return Math.Pow(xDistanceFromCenter, 2) / Math.Pow(Width / 2, 2) + Math.Pow(yDistanceFromCenter, 2) / Math.Pow(Height / 2, 2) < 1;
+		}
+
+		public override bool ClickableAt(int x, int y) {
+			Rectangle rect = GuiRectangle.GetGuiRectangle(Left, Top, Width, Height);
+			int lineThickness = GetFieldValueAsInt(FieldType.LINE_THICKNESS);
+			int lineThicknessPlusSafety = lineThickness + 10;
+
+			// If we clicked inside the rectangle and it's visible we are clickable at.
+			Color fillColor = GetFieldValueAsColor(FieldType.FILL_COLOR);
+			if (!Color.Transparent.Equals(fillColor)) {
+				if (Contains(x, y)) {
+					return true;
+				}
+			}
+
+			// check the rest of the lines
+			if (lineThicknessPlusSafety > 0) {
+				using (Pen pen = new Pen(Color.White, lineThicknessPlusSafety)) {
+					using (GraphicsPath path = new GraphicsPath()) {
+						path.AddEllipse(rect);
+						return path.IsOutlineVisible(x, y, pen);
+					}
+				}
+			} else {
+				return false;
+			}
+		}
+	}
+}