return HRESULTs instead of BOOLs so that errors can be properly
propagated from lower levels.

ole32: Fix the HGLOBAL stream IStream_Read function to return S_OK even if not all of the requested bytes were available.

wintrust: Change the name of the strings to not confuse them with the functions that are present in wintrust.

Based on the original systray implementation by Kai Morich <kai.morich@bigfoot.de>.

Replaces duplicated scrolling code with re-usable functions.
Removes excessive boundary checking on scroll code, since that's done
in the scrollbar control anyways.
Properly separates repaint calls based on what has changed.
Send EN_UPDATE and EN_CHANGE at the right places.
Only call EnsureVisible on changes, not all repaints.

This avoids having to generate all the headers before make depend.