https://github.com/AllenDang/w32/blob/master/user32.go#L369 seems to be broken. Worked before updating from a version that was months old, has something changed?
(win7 x64)
Easily replicated by grabbing skelterjohn/go.wde/wdetest and adding wd.LockSize(true) there.
panic: Failed to find GetWindowLongPtrW procedure in user32.dll: The specified procedure could not be found.
goroutine 1 [running]:
syscall.(_LazyProc).mustFind(0x1263ada0, 0x125fa9d0)
$GOPATH/src/pkg/syscall/dll_windows.go:234 +0x6b
syscall.(_LazyProc).Call(0x1263ada0, 0x1d1718, 0x2, 0x2, 0x2, ...)
$GOPATH/src/pkg/syscall/dll_windows.go:247 +0x32
github.com/AllenDang/w32.GetWindowLongPtr(0x41a62, 0xfffffff0, 0x5c3b94, 0x4)
$GOPATH/src/pkg/github.com/AllenDang/w32/user32.go:369 +0x71
github.com/skelterjohn/go.wde/win.(*Window).LockSize(0x1261b400, 0x5c3b01, 0x4)
$GOPATH/src/pkg/github.com/skelterjohn/go.wde/win/win_windows.go:132 +0x35
main.init┬À1()
$GOPATH/src/rain/graphics.go:37 +0x179
main.init()
$GOPATH/src/rain/rain.go:134 +0xfd
goroutine 2 [syscall]:
created by runtime.main
$GOPATH/src/pkg/runtime/proc.c:221
goroutine 3 [syscall]:
syscall.Syscall6(0x76a578e2, 0x4, 0x12600600, 0x41a62, 0x0, ...)
$GOPATH/src/pkg/runtime/zsyscall_windows_386.c:97 +0x49
syscall.(_Proc).Call(0x125fa820, 0x1d477c, 0x4, 0x4, 0x0, ...)
$GOPATH/src/pkg/syscall/dll_windows.go:119 +0x4e9
syscall.(_LazyProc).Call(0x1263aba0, 0x1d477c, 0x4, 0x4, 0x1d4788, ...)
$GOPATH/src/pkg/syscall/dll_windows.go:248 +0x4f
github.com/AllenDang/w32.GetMessage(0x12600600, 0x41a62, 0x0, 0x0, 0x1, ...)
$GOPATH/src/pkg/github.com/AllenDang/w32/user32.go:227 +0x94
github.com/skelterjohn/go.wde/win.(*Window).HandleWndMessages(0x1261b400, 0x125f4b00)
$GOPATH/src/pkg/github.com/skelterjohn/go.wde/win/win_windows.go:197 +0x59
github.com/skelterjohn/go.wde/win._func_004(0x12601538, 0x12601528, 0x12601530,0x125f4b00, 0x0, ...)
$GOPATH/src/pkg/github.com/skelterjohn/go.wde/win/win_windows.go:110 +0x83
created by github.com/skelterjohn/go.wde/win.NewWindow
$GOPATH/src/pkg/github.com/skelterjohn/go.wde/win/win_windows.go:111 +0xb9