Gtaph is erased while minimizing the graph window!

Question

Hi

I'm writing a monitoring system program displays a real time graph to a set of input values, when minimizing the graph window , the realtime graph is erased , and the form loading graph is still exist, how can i avoid erasing the graph while minimizing the graph window.

and how can i add a Hscrollbar to the graph window (panel window) when the graph reaches the max width of the graph panel?.