ShellClientsManager: centered windows are not always shell windows (#851)

* ShellClientsManager: centered windows are not always shell windows

* Remove positioned window line

Author: danirabbit

compositor/ShellClients/ShellClientsManager.vala

@@ -182,21 +182,32 @@ public class GreeterCompositor.ShellClientsManager : Object {
         window.unmanaging.connect_after ((_window) => positioned_windows.remove (_window));
     }
 
-    public void make_centered (Meta.Window window) requires (!is_itself_positioned (window)) {
+    public void make_centered (Meta.Window window) requires (!is_itself_shell_window (window)) {
         positioned_windows[window] = new ShellWindow (window, CENTER);
 
         // connect_after so we make sure that any queued move is unqueued
         window.unmanaging.connect_after ((_window) => positioned_windows.remove (_window));
     }
 
-    public bool is_itself_positioned (Meta.Window window) {
-        return (window in positioned_windows) || (window in panel_windows) || NotificationStack.is_notification (window);
+    public bool is_itself_shell_window (Meta.Window window) {
+        return (
+            (window in panel_windows) ||
+            NotificationStack.is_notification (window)
+        );
     }
 
-    public bool is_positioned_window (Meta.Window window) {
-        bool positioned = is_itself_positioned (window);
+    /**
+     * Whether the given window is a shell window. A shell window is a window that's
+     * part of the desktop shell itself and should be completely ignored by other components.
+     * It is entirely managed by Gala, always above everything else, and manages hiding
+     * in e.g. multitasking view itself. This also applies to transient windows of shell windows.
+     * Note that even if `false` is returned the window might still be in part managed by gala
+     * e.g. for centered windows.
+     */
+    public bool is_shell_window (Meta.Window window) {
+        bool positioned = is_itself_shell_window (window);
         window.foreach_ancestor ((ancestor) => {
-            if (is_itself_positioned (ancestor)) {
+            if (is_itself_shell_window (ancestor)) {
                 positioned = true;
             }
 

compositor/WindowManager.vala

@@ -31,7 +31,7 @@ namespace GreeterCompositor {
 
         /**
          * The group that contains all WindowActors that make shell elements, that is all windows reported as
-         * ShellClientsManager.is_positioned_window.
+         * ShellClientsManager.is_shell_window.
          * It will (eventually) never be hidden by other components and is always on top of everything. Therefore elements are
          * responsible themselves for hiding depending on the state we are currently in (e.g. normal desktop, open multitasking view, fullscreen, etc.).
          */
@@ -309,7 +309,7 @@ namespace GreeterCompositor {
 
         private void check_shell_window (Meta.WindowActor actor) {
             unowned var window = actor.get_meta_window ();
-            if (ShellClientsManager.get_instance ().is_positioned_window (window)) {
+            if (ShellClientsManager.get_instance ().is_shell_window (window)) {
                 Utils.clutter_actor_reparent (actor, shell_group);
             }