The Old New Thing : Common gotchas when writing your own p/invoke

The Old New Thing : Common gotchas when writing your own p/invoke: "n 64-bit Windows, the LONG and DWORD members are four bytes, but the dwExtraInfo is a ULONG_PTR, which is eight bytes on a 64-bit machine. Since Windows assumes /Zp8 packing, the dwExtraInfo must be aligned on an 8-byte boundary, which forces four bytes of padding to be inserted after the time to get the dwExtraInfo to align properly. And in order for all this to work, the MOUSEINPUT structure itself must be 8-byte aligned."