virt-manager: Only save window dimensions on app exit (bz 1262561)

Rather than on every window change event which spams dconf and hits
the disk repeatedly. The new method is roughly what is suggested by
https://wiki.gnome.org/HowDoI/SaveWindowState

https://bugzilla.redhat.com/show_bug.cgi?id=1262561

virtManager/details.py

@@ -395,6 +395,7 @@ class vmmDetails(vmmGObjectUI):
         if h <= 0:
             h = 600
         self.topwin.set_default_size(w, h)
+        self._window_size = None
 
         self.oldhwkey = None
         self.addhwmenu = None
@@ -586,6 +587,9 @@ class vmmDetails(vmmGObjectUI):
         self.snapshots.cleanup()
         self.snapshots = None
 
+        if self._window_size:
+            self.vm.set_details_window_size(*self._window_size)
+
         self.vm = None
         self.conn = None
         self.addhwmenu = None
@@ -1030,11 +1034,9 @@ class vmmDetails(vmmGObjectUI):
     ##########################
 
     def window_resized(self, ignore, event):
-        # Sometimes dimensions change when window isn't visible
         if not self.is_visible():
             return
-
-        self.vm.set_details_window_size(event.width, event.height)
+        self._window_size = (event.width, event.height)
 
     def popup_addhw_menu(self, widget, event):
         ignore = widget

virtManager/manager.py

@@ -122,6 +122,7 @@ class vmmManager(vmmGObjectUI):
         w, h = self.config.get_manager_window_size()
         self.topwin.set_default_size(w or 550, h or 550)
         self.prev_position = None
+        self._window_size = None
 
         self.vmmenu = vmmenu.VMActionMenu(self, self.current_vm)
         self.connmenu = Gtk.Menu()
@@ -238,6 +239,10 @@ class vmmManager(vmmGObjectUI):
         self.connmenu = None
         self.connmenu_items = None
 
+        if self._window_size:
+            self.config.set_manager_window_size(*self._window_size)
+
+
     def is_visible(self):
         return bool(self.topwin.get_visible())
 
@@ -459,11 +464,9 @@ class vmmManager(vmmGObjectUI):
     ####################
 
     def window_resized(self, ignore, event):
-        # Sometimes dimensions change when window isn't visible
         if not self.is_visible():
             return
-
-        self.config.set_manager_window_size(event.width, event.height)
+        self._window_size = (event.width, event.height)
 
     def exit_app(self, src_ignore=None, src2_ignore=None):
         self.emit("action-exit-app")