How to use double clicking a record in a grid to activate a form?

This code in the grid class's Init:

*** now make sure that the dblclick method of all the contained text boxes
*** delegate to the grid's dblclick()
FOR lnCol = 1 TO This.ColumnCount
  loColumn = This.Columns[ lnCol ]
  FOR EACH loControl IN loColumn.Controls
      IF PEMSTATUS( loControl, [dblClick], 5 )      
        BINDEVENT( loControl, 'dblClick', This, 'dblClick' )  
      ENDIF
  ENDFOR
ENDFOR

Now, in the instance of the grid on the form you can put this code in the grid's dblclick()

DO FORM MyChildForm NAME loChildForm LINKED

And also, can a combobox be used in a grid?

Go to the tools and utilities page of my web site and download the white paper and code samples from my conference presentation called "How to Put a Combo in a Grid". You will have all the information (and examples) that you need.