A couple of items with respect to 'Dealing with Masked Elements'

a) First paragraph on page 815; 3rd line.
'Select the Messages toolbar button in the Properties window for the class and double-click the message ID ID_ELEMENT_SENDTOBACK.'
Should be:
'Select the Events toolbar button in the Properties window for the class and double-click the message ID ID_ELEMENT_SENDTOBACK.'



b) In addition to code shown, for SketcherDoc.cpp, an extra line is needed in the SketcherDoc.h
After :
.
.
.
POSITION GetListHeadPosition() // return list head POSITION value
      { return m_ElementList.GetHeadPosition(); }
CElement* GetNext(POSITION& aPos) // Return current element pointer
      { return m_ElementList.GetNext(aPos); }

Add:

void SendToBack(CElement* pElement); // Move an element to the back in the Z-order