Change size of Windows Taskbar

I need a C++ program that changes the size of the Windows taskbar. The Windows taskbar normally occupies the full bottom edge of the primary monitor, but I want it to occupy only the left side of the bottom edge (say 500 pixels wide). I want a C/C++ program that uses Win32 API to change the size of the taskbar programmatically. When the program is started, the taskbar should shrink in width from the screen width to 500 pixels, and it's height should remain same as before. It should allow all other normal operations of the taskbar such as resizing it's height by dragging it's top egde, docking it to the other edges of the monitor, etc.