Unlike the symbian phones most Nokia s40 cannot open two windows/platforms at the same time. This have bothered me many times, if i want to make a call or check a contact while using a application, I need to exit the application. But there is tweak to do it without closing the application.(works only if the mobile support PTT-push to talk)

First go to PTT settings & make the 'PTT key default function' to 'open contactlist'.
Open the application, now there will be shortcut button for PTT in your mobile(for nokia 6233 top-left corner near the speaker)it will open the PTT menu. Now you can add any contacts from to your PTT and use other funtions without closing the application. For making call by pressing the green call button, To view video or pic click add contact and then select any contact and press add details there select your choice like pic or video..etc