Tests to validate return value of the LVM_GETORIGIN message and fix our
implementation.

The native control has a 2 pixel header. This implements that background pixel
line and the gridline below it.

Implement basic LVS_EX_GRIDLINES functionality including support for no items.

Take a reference to the ibasefilter and request it for the pins and a
cookie. This seems to be the easiest way to ensure correctness.

This necessary piece of code was lost. Restore it.

winhelp: We can reference any page in HLPFILE_BrowsePage(). Perform similar change in HLPFILE_DoReadHlpFile() for the symmetry.