Many years ago, the Window Functionality Suite (WFS) library was created by Aaron Ballman. This library was a collection of Win32 Declares (and a few other things) for accessing Windows-specific functionality that was not directly provided by the Xojo framework.
WFS is still available on GitHub, but it has languished over the years. For example, it has lots of legacy code in it for older versions of Windows that is no longer needed since Xojo only supports Windows 7 and later. WFS is also not really compatible with 64-bit projects since the Declares mostly assume 32-bit or bust.
To that end, I’ve started a new open-source project called WinAPILib that is now available on GitHub.