is this possible

[mithu]

I have a spreadsheet that i use for forecasting each week.. we
basically look at the previous weeks sales and anything our business
parters have in the pipeline and forecast for the following week..
is there anyway to have a window come up.. like a comment window comes
up and show a graph of previous revenue? I have all the raw data for
weekly revenue for the last 3 months in a different worksheet..

so bascailly what i want it to do is when i click in the cell to enter
the forecast.. in similar style to the comment window i want to show a
graph of the past revenue.

is this possible?