There is pseudocode of simplier version

abstract class PictureBase // base class for all objects
{
      public Rectangle Bounds {get;set;}    // contains the topleft
corner (position) of object and its width and height
      // when your object has not a rectangle shape, you should
implement you own class for boundaries

      public abstract void Draw(Graphics gr); // draws the content
and setup property Bounds
      // example - if method draws a rectangle  with size (10,10) at
point of topleft corner (100,100), you should use these values for
Bounds property.

      public string Tip {get;set;}  // the string for showing when
mouse is moving over the objec
      public System.Windows.Forms.Cursor Cursor {get;set;}  // the
cursor for using when mouse is moving over the object
}

class View  // this is usercontrol or panel which contains a canvas
control or it is the class of canvas :-)
{
// to do

       // this method shoul be called on each move move event
       void TrackMouseMove()
       {
               // CheckHitTest - the method which uses
PictureBase.Bounds property and determines the object under the mouse
pointer.
               //Usually it iterates through all objects and return
an object which Bounds contains  mouse position.
               PictureBase   htObj =
CheckHitTest(m_lastMouseMovePos);
                               if(htObj == null)
               {
                       m_canvas.Cursor = m_defaultCursor; // set
default cursor
                       return;
               }
               if (m_lastHoveredObj != htObj) // another object under
the mouse
               {
                       m_tooltip.Active = false;
                       m_tooltip.SetToolTip(m_canvas, (htObj !=
null) ? htObj.Tip : null);
                               m_tooltip.Active = (htObj != null);
                       m_canvas.Cursor = htObject.Cursor;
                       m_lastHoveredObj = htObj;
               }
       }