diff --git a/share/manifest b/share/manifest
index e6f8a37..92f8e91 100644
--- a/share/manifest
+++ b/share/manifest
@@ -50,6 +50,8 @@ $css
 # entry point of pdf2htmlEX.Viewer
 # You can override default configuration by passing an object to the constructor of Viewer
 # Refer to DEFAULT_CONFIG in viewer.js for possible keys
+# E.g.
+# new pdf2htmlEX.Viewer({ 'preload_pages' : 1 });
 @pdf2htmlEX.min.js
 """
 <script>
diff --git a/share/pdf2htmlEX.js.in b/share/pdf2htmlEX.js.in
index 5b379a3..659071a 100644
--- a/share/pdf2htmlEX.js.in
+++ b/share/pdf2htmlEX.js.in
@@ -534,17 +534,13 @@
       this.scroll_to(this.page_map[active_page.n], [0,0]);
     },
 
+    // TODO: preserve active_page idx after rescaling
     get_active_page : function () {
-      // get page that are on the center of the view     //TODO better on top?!
-      var y_center = this.$container.offset().top + this.$container.height() / 2;
-      var pl = this.pages;
-      var last_page = -1;
       for(var i = 0, l = pl.length; i < l; ++i) {
-        if (pl[i].$p.offset().top > y_center)
-          break;
-        last_page = i;
+        if (pl[i].is_visible())
+          return pl[i];
       }
-      return pl[last_page];
+      return;
     },
 
     get_containing_page : function(obj) {
@@ -568,7 +564,7 @@
 
       // cur_page might be undefined, e.g. from Outline
       var cur_page = _.get_containing_page(t);
-      if(cur_page !== undefined)
+      if(cur_page)
       {
         cur_pos = cur_page.position();
         //get the coordinates in default user system