WinDowse is a great free application that lets you know technical information about a window such as handles, control hierarchy, classes, modules, exe information, colours and coordinates and much much more.
As an example, by hovering the mouse over the IE address bar you can find the handle and class name of the control that contains the URL from IE:
From the WinDowse website:
text, caption, resource ID, process ID, application instance handle, window handle, parent handle, function address, menu handle, coordinates in parent, coordinates in screen, size, client area size, style, extended style, class name, class function address, icon handle, small icons handle, cursor handle, background brush handle, module handle, class style, list of parent hierarchy, recursive list of children, list of windows under the mouse cursor, full tree of all windows in the system with auto-selecting the current window, exe file path, exe file name, original file name, file description, file version, product name, internal name, legal copyright, legal trademarks, product version, company name, comments from the version information, list of modules used by selected window's application with full paths, absolute cursor position, relative cursor position on window coordinates, relative cursor position on window client area coordinates, color of the pixel under mouse cursor.
to copy any information about the selected window into clipboard, to find any window by text, class name or handle, to modify the window's text, origin or size, to show/hide the window, to enable/disable the window, to make any user action with the selected window by installable plugins, to see the zoomed window image.
WinDowse web site