I am a CellSheet

I add a new Cell to myself

I change the value of one of my Cells

I recalculate my value

I announce that my value has changed (A1,B1)

I am a SpreadsheetSumSheet

I get a message that I am interested in (A1), value of one of my CellSheets has changed

I send message to all my CellSheets to return their value (A2)

I recalculate my value

I announce that my value has changed (B3)

I am a Cell

CellSheets tells me to change my value

I change my value

I announce that my value has changed (A3)

I am a CellAverageSheet

I get a message that I am interested in (A3), value of one of my Cells has changed

I send message to all my Cells to return their value (A4)

I recalculate my value

I announce that my value has changed (B5)

I am a SpreadsheetViewContainer (for CellSheet)

I get a message that I am interested in (B1), value of my object has changed

I send it a message to return its value and its list of values in its collection (B2)

I display the new value and the new list

I am a SpreadsheetViewContainer (for SpreadsheetSumSheet)

I get a message that I am interested in (B3), value of my object has changed

I send it a message to return its value and its list of values in its collection (B4)

I display the new value and the new list

I am a SpreadsheetViewContainer (for CellAverageSheet)

I get a message that I am interested in (B5), value of my object has changed

I send it a message to return its value and its list of values in its collection (B6)

I display the new value and the new list