C#

• ParentForm - The MDI Parent
• ChildFormA - One of the child forms
• ChildFormB - Another child form
• ChildFormC - The last child form
• DataA - Data class for ChildFormA
• DataB - Data class for ChildFormB
• DataC - Data class for ChildFormC

• childA - ChildFormA
• childB - ChildFormB
• childC - ChildFormC

public void SendToChildA(DataA data)
{
  childA.Data = data;
  childA.DataSent();
}

....
// Going to send data to ChildFormB
ParentForm parent = this.Parent as ParentForm;
 
DataB data = new DataB();
// fill out data class
 
parent.SendToChildB(data);
....

protected override void OnMouseOver(System.Windows.Form.MouseEventArgs mea)
{
mea.<code>[SomeMethod()]</code>
}

Control m_ctrl = this.GetChildAtPoint(new System.Drawing.Point( e.X, e.Y));<br />
// check if !null then...<br />
Control m_subCtrl = m_ctrl.GetChildAtPoint(new System.Drawing.Point( e.X - m_ctrl.Left, e.Y - m_ctrl.Top ));<br />
//...

Point pt		= new Point(x, y);
Control parent	= this;
Control child	= parent.GetChildAtPoint(pt);
while (null != child)
{
	pt = parent.PointToScreen(pt);
	pt = child.PointToClient(pt);
	parent = child;
	child = parent.GetChildAtPoint(pt);
}
// parent now contains the control at x,y

Point pt		= new Point(x, y);
Control parent	= this;
Control child	= parent.GetChildAtPoint(pt);
if (null != child)
{
	pt = parent.PointToScreen(pt);
	do
	{
		parent = child;
		child = parent.GetChildAtPoint(parent.PointToClient(pt));
	} while (null != child);
}
// parent now contains the control at x,y