I recommend you to check the following link, it has almost 500,000 lines VC++ Source Code, but it is not free:
http://www.ucancode.net
It ships with:
-- Label & Report Source Code Solution
-- SCADA & HMI Source Code Solution
-- Process Simulation Source Code Solution
-- Graphics Drawing Source Code Solution
-- GIS Source Code Solution
-- Real- data display source code Solution
-- Flow Chart & Diagram Source Code Solution
-- BPM & Workflow Diagram Source Code Solution
-- E-Form Source Code Solution
... ...
Or GUI ToolKit with:
http://www.bcgsoft.com