Converting double hung windows to doorway

Hi, I'm trying to run shelves across a picture window to hold glass dishes etc. We had shelves there with L brackets attached to the wooden cross pieces of the wooden inserts. We have a new window that has no external cross pieces. I wanted any ideas on how to brace the centers without using wood pieces between the shelves. Thanks, Pappy321

We're noticing a lot of condensation on our windows. Where's it all coming from? We're in a small house in San Diego. It has a single wall-furnace. It's typically about 70F inside the house, and the outside has been between 35-60F (it's been relatively cold here), and we've had rain on/off for the last couple of weeks, so the ground is wet/moist. I think/hope the condensation is normal but I'm worried this could be a sign of a problem that could grow into something serious. What amount of condensation should we be worried about? We have not noticed any mold yet, except a little bit on the bathroom tiles. Our windows are old, single-paned windows, so I think the house isn't all that air-tight. Should I be worried? Thanks.