10 files changed, 13 insertions(+), 61 deletions(-)

M app/app.go
M app/doc.go
M app/os_android.go
M app/os_ios.go
M app/os_js.go
M app/os_macos.go
M app/os_unix.go
M app/os_windows.go
M app/runmain.go
M app/window.go

@@ 120,18 120,6 @@ func DataDir() (string, error) {
 	return dataDir()
 }
 
-// Main must be called last from the program main function.
-// On most platforms Main blocks forever, for Android and
-// iOS it returns immediately to give control of the main
-// thread back to the system.
-//
-// Calling Main is necessary because some operating systems
-// require control of the main thread of the program for
-// running windows.
-func Main() {
-	osMain()
-}
-
 func (FrameEvent) ImplementsEvent() {}
 
 func init() {

@@ 33,28 33,12 @@ For example:
 A program must keep receiving events from the event channel until
 [DestroyEvent] is received.
 
-# Main
+# Main Thread
 
-The Main function must be called from a program's main function, to hand over
-control of the main thread to operating systems that need it.
-
-Because Main is also blocking on some platforms, the event loop of a Window must run in a goroutine.
-
-For example, to display a blank but otherwise functional window:
-
-	package main
-
-	import "gioui.org/app"
-
-	func main() {
-		go func() {
-			w := app.NewWindow()
-			for {
-				w.Event()
-			}
-		}()
-		app.Main()
-	}
+Some GUI platform need access to the main thread of the program. To avoid a
+deadlock on such platforms, at least one Window must have its Event method
+called by the main goroutine. It doesn't have to be any particular Window;
+even a destroyed Window suffices.
 
 # Permissions
 

@@ 1317,9 1317,6 @@ func findClass(env *C.JNIEnv, name string) C.jclass {
 	return C.jni_FindClass(env, cn)
 }
 
-func osMain() {
-}
-
 func newWindow(window *callbacks, options []Option) {
 	mainWindow.in <- windowAndConfig{window, options}
 	<-mainWindow.windows

@@ 388,9 388,6 @@ func newWindow(win *callbacks, options []Option) {
 	<-mainWindow.windows
 }
 
-func osMain() {
-}
-
 //export gio_runMain
 func gio_runMain() {
 	runMain()

@@ 741,10 741,6 @@ func (w *window) navigationColor(c color.NRGBA) {
 	theme.Set("content", fmt.Sprintf("#%06X", []uint8{rgba.R, rgba.G, rgba.B}))
 }
 
-func osMain() {
-	select {}
-}
-
 func translateKey(k string) (key.Name, bool) {
 	var n key.Name
 

@@ 1012,15 1012,6 @@ func (w *window) init() error {
 	return nil
 }
 
-func osMain() {
-	C.gio_initApp()
-	close(launched)
-	for {
-		C.dispatchEvent()
-		gio_dispatchMainFuncs()
-	}
-}
-
 func convertKey(k rune) (key.Name, bool) {
 	var n key.Name
 	switch k {

@@ 33,10 33,6 @@ type WaylandViewEvent struct {
 func (WaylandViewEvent) implementsViewEvent() {}
 func (WaylandViewEvent) ImplementsEvent()     {}
 
-func osMain() {
-	select {}
-}
-
 type windowDriver func(*callbacks, []Option) error
 
 // Instead of creating files with build tags for each combination of wayland +/- x11

@@ 85,10 85,6 @@ var resources struct {
 	cursor syscall.Handle
 }
 
-func osMain() {
-	select {}
-}
-
 func newWindow(win *callbacks, options []Option) {
 	done := make(chan struct{})
 	go func() {

@@ 25,6 25,6 @@ func runMain() {
 		// Indirect call, since the linker does not know the address of main when
 		// laying down this package.
 		fn := mainMain
-		fn()
+		go fn()
 	})
 }

@@ 684,6 684,13 @@ func (w *Window) processEvent(e event.Event) bool {
 
 // Event blocks until an event is received from the window, such as
 // [FrameEvent], or until [Invalidate] is called.
+//
+// Note: if more than one Window is active, at least one must have
+// its Event called from the main goroutine that runs the main
+// function. This is necessary because some operating system GUI
+// implementations require control of the main thread.
+// For this reason, it is allowed to call Event even after a
+// DestroyEvent has been received.
 func (w *Window) Event() event.Event {
 	w.init()
 	return w.basic.Event()