Tobias Häußler authored Jul 18, 2011 and Jon Turney committed Nov 27, 2012

I created a small patch for XWin that adds correct grouping of taskbar icons
when 'Always combine, hide labels' is set in the taskbar properties. It uses the
new taskbar APIs introduced in Windows 7 to set an application id for each
window. The id is based on the X11 class hints.

v2: Add file to _SOURCES to fix distcheck

v3 : Fix compilation with mingw-w64 w32api headers
Include propkey.h, propsys.h rather than defining necessary stuff ourselves

v4: Fix up names taskbar->propertystore, AppID->AppUserModelID, etc.
Link directly with ole32 for PropVariantClear(), prototyping it if neccessary.

v5: Put winSetAppUserModelID()-related code in a separate file.
Drop a superfluous assign to hr of ignored HRESULT of SetValue()

Signed-off-by: Tobias Häußler <tobias.haeussler@gmx.de>
Reviewed-by: Jon TURNEY <jon.turney@dronecode.org.uk>
Reviewed-by: Colin Harrison <colin.harrison@virgin.net>