Bugfix: Window focus linked list

It used to be possible to confuse the window manager in the
CloseActiveWindow() function and the linked list got all broken. Seems
more reliable now! Added function PrintWindows() to inspect the linked
lists.

supervisor.go

@@ -87,7 +87,6 @@ type Supervisor struct {
 
 	// List of window focus history for Window Manager.
 	winFocus  *FocusedWindow
-	winTop    *FocusedWindow // pointer to top-most window
 	winBottom *FocusedWindow // pointer to bottom-most window
 }
 

window_manager.go

@@ -66,7 +66,6 @@ func (s *Supervisor) addWindow(win *Window) {
 		s.winFocus = &FocusedWindow{
 			window: win,
 		}
-		s.winTop = s.winFocus
 		s.winBottom = s.winFocus
 		win.SetFocus(true)
 	} else {
@@ -138,7 +137,6 @@ func (s *Supervisor) FocusWindow(win *Window) error {
 		s.winFocus = target
 
 		// Fix the top and bottom pointers.
-		s.winTop = s.winFocus
 		if newBottom != nil {
 			s.winBottom = newBottom
 		}
@@ -184,13 +182,44 @@ func (s *Supervisor) CloseAllWindows() int {
 func (s *Supervisor) CloseActiveWindow() bool {
 	var node = s.winFocus
 	if node != nil {
-		node.window.Destroy()
 		node.window.Hide()
-		s.winFocus = node.next
-		s.winFocus.window.SetFocus(true)
-		return true
 	}
-	return false
+
+	// Find the next visible window to focus.
+	for node != nil {
+		if !node.window.Hidden() {
+			s.FocusWindow(node.window)
+			break
+		}
+		node = node.next
+	}
+
+	return true
+}
+
+// PrintWindows is a debug function that walks the window tree and prints them to your console.
+func (s *Supervisor) PrintWindows() {
+	var (
+		node = s.winBottom
+		i    int
+	)
+
+	fmt.Println("From the bottom:")
+	for node != nil {
+		i++
+		fmt.Printf("%d. %s  focused=%+v  hidden=%+v\n", i, node.window, node.window.Focused(), node.window.Hidden())
+		node = node.prev
+	}
+
+	node = s.winFocus
+	i = 0
+
+	fmt.Println("Focus order:")
+	for node != nil {
+		i++
+		fmt.Printf("%d. %s  focused=%+v  hidden=%+v\n", i, node.window, node.window.Focused(), node.window.Hidden())
+		node = node.next
+	}
 }
 
 // presentWindows draws the windows from bottom to top.