抓取窗体，弹出窗口和菜单

I'm developing an application the screen grab a thrid party app. Right now I've no problem in finding all the belonging forms, menus and popups in the 3rd party app I plan to grab, but i don't know how can I findout if the window I'm grabbing is a popup or a menu or whatever. Is there any function that given the window handle tells me what of window it is ?I'm developing an application the screen grab a