While making builds of Hexchat (an IRC client that uses GTK) for Windows, I've run into a snag. In the file gtkstatusicon.c, the function

    gtk_status_icon_init(GtkStatusIcon *status_icon)

has this line:

    priv->nid.uID = GPOINTER_TO_UINT (status_icon);

where priv->nid is a NOTIFYICONDATAW ( http://msdn.microsoft.com/en-us/library/windows/desktop/bb773352 ) and nid.uID is a UINT.

On Windows x64, uint's are only 32 bits in size, so this assignment loses the upper 32-bits of the pointer. Later, when this pointer is dereferenced in wndproc(), this causes a segfault.

This is GTK 2.24.17

I asked on #gtk+ about this, and walters said GPOINTER_TO_UINT is only supposed to be used on something which should have fit in a uint in the first place. The status_icon pointer on Windows 7 does always seem to have all zeros in the upper 32 bits, but the same pointer in Windows 8 always has something in the upper 32 bits, so it seems it happens to work on Windows 7 only because of a coincidence.