Dialog: Notify page stack change after closing

See also: https://github.com/gpodder/gpodder-bb10/issues/7

touch/Dialog.qml

@@ -36,7 +36,10 @@ Rectangle {
         pgst.topOfStackChanged();
     }
 
-    Component.onDestruction: pgst.dialogsVisible = pgst.dialogsVisible - 1;
+    Component.onDestruction: {
+        pgst.dialogsVisible = pgst.dialogsVisible - 1;
+        pgst.onDialogDismissed(page);
+    }
 
     default property alias children: contents.children
     property bool isDialog: true

touch/Main.qml

@@ -102,6 +102,19 @@ Item {
     property string menuButtonIcon: ''
     property string windowTitle: 'gPodder'
 
+    function onDialogDismissed(dialog) {
+        for (var i=0; i<children.length; i++) {
+            // If the dismissed dialog is not on top of the stack, it was
+            // dismissed while another page was pushed, so we need to do
+            // another topOfStackChanged() to get the right top item
+            // (see https://github.com/gpodder/gpodder-bb10/issues/7)
+            if (children[i] === dialog && i < children.length - 1) {
+                topOfStackChanged();
+                break;
+            }
+        }
+    }
+
     function topOfStackChanged(offset) {
         if (offset === undefined) {
             offset = 0;