combined fix of segfaults, leaks and invisible windows

Test case: while :; do create window; read; destroy window; done
The culprit is that the new window might get the same XID as the
just-destroyed one, confusing the window manager.

 * src/mwindowpropertycache.cpp (MWindowPropertyCache::~MWindowPropertyCache):
   Stop tracking damages, ensuring that the Damage object is destroyed.
 * src/mdecoratorframe.cpp (MDecoratorFrame::setManagedWindow):
   Disconnect from the managed window's destroyed() signal properly.
 * src/mcompositemanager.cpp (MCompositeManagerPrivate::destroyEvent):
   Remove the destroyed window's MWindowPropertyCache from the list of
   caches, because we don't want to and shouldn't reuse it.
 * src/mcompositewindow.cpp (MCompositeWindow::~MCompositeWindow):
   -- delete timers
   -- stop damage tracking
   -- do not attempt to remove ourselves from the stacking_list,
      because there might be already another object with the same XID.

4 files changed, 11 insertions, 3 deletions

diff --git a/src/mcompositemanager.cpp b/src/mcompositemanager.cpp
index 5ce457d..6241d19 100644
--- a/src/mcompositemanager.cpp
+++ b/src/mcompositemanager.cpp
@@ -926,7 +926,10 @@ void MCompositeManagerPrivate::destroyEvent(XDestroyWindowEvent *e)
     if (item) {
         item->deleteLater();
         removeWindow(item->window());
-        // PC deleted with the MCompositeWindow
+        prop_caches.remove(item->window());
+        // PC deleted with the MCompositeWindow.  Till then we've made sure
+        // that we can't reuse it, even if a window with the same XID is
+        // created before @item is actually destroyed.
     } else {
         // We got a destroy event from a framed window (or a window that was
         // never mapped)
diff --git a/src/mcompositewindow.cpp b/src/mcompositewindow.cpp
index 62b116a..b3f60e6 100644
--- a/src/mcompositewindow.cpp
+++ b/src/mcompositewindow.cpp
@@ -119,17 +119,20 @@ MCompositeWindow::MCompositeWindow(Qt::HANDLE window,
 MCompositeWindow::~MCompositeWindow()
 {
     MCompositeManager *p = (MCompositeManager *) qApp;
-    p->d->removeWindow(window());
 
     if (window() && (t_ping || t_reappear)) {
         stopPing();
+        delete t_ping;
+        delete t_reappear;
         t_ping = t_reappear = 0;
     }
     endAnimation();
     
     anim = 0;
+    delete damage_timer;
     
     if (pc) {
+        pc->damageTracking(false);
         p->d->prop_caches.remove(window());
         pc->deleteLater();
     }    
diff --git a/src/mdecoratorframe.cpp b/src/mdecoratorframe.cpp
index bd7012c..3ae6e80 100644
--- a/src/mdecoratorframe.cpp
+++ b/src/mdecoratorframe.cpp
@@ -92,7 +92,8 @@ void MDecoratorFrame::setManagedWindow(MCompositeWindow *cw,
 
     if (client == cw)
         return;
-    disconnect(this, SLOT(destroyClient()));
+    if (client)
+        disconnect(client, SIGNAL(destroyed()), this, SLOT(destroyClient()));
     client = cw;
 
     qulonglong winid = client ? client->window() : 0;
diff --git a/src/mwindowpropertycache.cpp b/src/mwindowpropertycache.cpp
index ce31f77..8e9d131 100644
--- a/src/mwindowpropertycache.cpp
+++ b/src/mwindowpropertycache.cpp
@@ -280,6 +280,7 @@ MWindowPropertyCache::~MWindowPropertyCache()
         shapeRegion();
     if (!net_wm_state_valid)
         netWmState();
+    damageTracking(false);
 }
 
 bool MWindowPropertyCache::hasAlpha()