app/internal/window: block Main until all windows are closed

With this change, the Wayland backend now supports multiple windows.

Signed-off-by: Elias Naur <mail@eliasnaur.com>

app/internal/window/os_unix.go

@@ -8,10 +8,16 @@ import (
 	"errors"
 )
 
-var mainDone = make(chan struct{})
+// windowCounter keeps track of the number of windows.
+// A send of +1 or -1 represents a change in window count.
+var windowCounter = make(chan int)
 
 func Main() {
-	<-mainDone
+	// Wait for first window
+	count := <-windowCounter
+	for count > 0 {
+		count += <-windowCounter
+	}
 }
 
 // instead of creating files with build tags for each combination of wayland +/- x11

app/internal/window/os_wayland.go

@@ -179,13 +179,18 @@ func newWLWindow(window Callbacks, opts *Options) error {
 		d.destroy()
 		return err
 	}
+	// Increment window counter.
+	windowCounter <- +1
 	w.w = window
 	go func() {
+		defer func() {
+			// Decrement window counter.
+			windowCounter <- -1
+		}()
 		w.w.SetDriver(w)
 		w.loop()
 		w.destroy()
 		d.destroy()
-		close(mainDone)
 	}()
 	return nil
 }

app/internal/window/os_x11.go

@@ -422,12 +422,16 @@ func newX11Window(gioWin Callbacks, opts *Options) error {
 	// make the window visible on the screen
 	C.XMapWindow(dpy, win)
 
+	// Increment window counter.
+	windowCounter <- +1
 	go func() {
+		defer func() {
+			windowCounter <- -1
+		}()
 		w.w.SetDriver(w)
 		w.setStage(system.StageRunning)
 		w.loop()
 		w.destroy()
-		close(mainDone)
 	}()
 	return nil
 }