Implement new Go based Desktop app

This focuses on Windows first, but coudl be used for Mac
and possibly linux in the future.

app/tray/wintray/w32api.go

@@ -0,0 +1,89 @@
+//go:build windows
+
+package wintray
+
+import (
+	"runtime"
+
+	"golang.org/x/sys/windows"
+)
+
+var (
+	k32 = windows.NewLazySystemDLL("Kernel32.dll")
+	u32 = windows.NewLazySystemDLL("User32.dll")
+	s32 = windows.NewLazySystemDLL("Shell32.dll")
+
+	pCreatePopupMenu       = u32.NewProc("CreatePopupMenu")
+	pCreateWindowEx        = u32.NewProc("CreateWindowExW")
+	pDefWindowProc         = u32.NewProc("DefWindowProcW")
+	pDestroyWindow         = u32.NewProc("DestroyWindow")
+	pDispatchMessage       = u32.NewProc("DispatchMessageW")
+	pGetCursorPos          = u32.NewProc("GetCursorPos")
+	pGetMessage            = u32.NewProc("GetMessageW")
+	pGetModuleHandle       = k32.NewProc("GetModuleHandleW")
+	pInsertMenuItem        = u32.NewProc("InsertMenuItemW")
+	pLoadCursor            = u32.NewProc("LoadCursorW")
+	pLoadIcon              = u32.NewProc("LoadIconW")
+	pLoadImage             = u32.NewProc("LoadImageW")
+	pPostMessage           = u32.NewProc("PostMessageW")
+	pPostQuitMessage       = u32.NewProc("PostQuitMessage")
+	pRegisterClass         = u32.NewProc("RegisterClassExW")
+	pRegisterWindowMessage = u32.NewProc("RegisterWindowMessageW")
+	pSetForegroundWindow   = u32.NewProc("SetForegroundWindow")
+	pSetMenuInfo           = u32.NewProc("SetMenuInfo")
+	pSetMenuItemInfo       = u32.NewProc("SetMenuItemInfoW")
+	pShellNotifyIcon       = s32.NewProc("Shell_NotifyIconW")
+	pShowWindow            = u32.NewProc("ShowWindow")
+	pTrackPopupMenu        = u32.NewProc("TrackPopupMenu")
+	pTranslateMessage      = u32.NewProc("TranslateMessage")
+	pUnregisterClass       = u32.NewProc("UnregisterClassW")
+	pUpdateWindow          = u32.NewProc("UpdateWindow")
+)
+
+const (
+	CS_HREDRAW          = 0x0002
+	CS_VREDRAW          = 0x0001
+	CW_USEDEFAULT       = 0x80000000
+	IDC_ARROW           = 32512 // Standard arrow
+	IDI_APPLICATION     = 32512
+	IMAGE_ICON          = 1          // Loads an icon
+	LR_DEFAULTSIZE      = 0x00000040 // Loads default-size icon for windows(SM_CXICON x SM_CYICON) if cx, cy are set to zero
+	LR_LOADFROMFILE     = 0x00000010 // Loads the stand-alone image from the file
+	MF_BYCOMMAND        = 0x00000000
+	MFS_DISABLED        = 0x00000003
+	MFT_SEPARATOR       = 0x00000800
+	MFT_STRING          = 0x00000000
+	MIIM_BITMAP         = 0x00000080
+	MIIM_FTYPE          = 0x00000100
+	MIIM_ID             = 0x00000002
+	MIIM_STATE          = 0x00000001
+	MIIM_STRING         = 0x00000040
+	MIIM_SUBMENU        = 0x00000004
+	MIM_APPLYTOSUBMENUS = 0x80000000
+	NIF_ICON            = 0x00000002
+	NIF_INFO            = 0x00000010
+	NIF_MESSAGE         = 0x00000001
+	SW_HIDE             = 0
+	TPM_BOTTOMALIGN     = 0x0020
+	TPM_LEFTALIGN       = 0x0000
+	WM_CLOSE            = 0x0010
+	WM_USER             = 0x0400
+	WS_CAPTION          = 0x00C00000
+	WS_MAXIMIZEBOX      = 0x00010000
+	WS_MINIMIZEBOX      = 0x00020000
+	WS_OVERLAPPED       = 0x00000000
+	WS_OVERLAPPEDWINDOW = WS_OVERLAPPED | WS_CAPTION | WS_SYSMENU | WS_THICKFRAME | WS_MINIMIZEBOX | WS_MAXIMIZEBOX
+	WS_SYSMENU          = 0x00080000
+	WS_THICKFRAME       = 0x00040000
+)
+
+// Not sure if this is actually needed on windows
+func init() {
+	runtime.LockOSThread()
+}
+
+// The POINT structure defines the x- and y- coordinates of a point.
+// https://msdn.microsoft.com/en-us/library/windows/desktop/dd162805(v=vs.85).aspx
+type point struct {
+	X, Y int32
+}