Help with AS/Min and Max Width Stage Align Stuff?

I could use some help figuring out how to do the following.

I want to have a rounded corner rectangular white box with drop shadow that will have a minimum width of 700px and a maximum width of 900px and contain a left hand aligned area 200px wide that slides in and out if you rollover the edge on the left. Can anyone help me with this or point me in the right direction?