auto merge of #647 : tkuehn/servo/master, r=metajack

This will be necessary for the constellation to properly assign sizes to iframes when a parent layout performs reflow.

6 files changed, 144 insertions, 106 deletions

diff --git a/src/components/main/constellation.rs b/src/components/main/constellation.rs
index b5783533da9..6c3d16e7420 100644
--- a/src/components/main/constellation.rs
+++ b/src/components/main/constellation.rs
@@ -43,12 +43,25 @@ pub struct Constellation {
 }
 
 /// Stores the Id of the outermost frame's pipeline, along with a vector of children frames
-#[deriving(Clone)]
 struct FrameTree {
     pipeline: @mut Pipeline,
     parent: Option<@mut Pipeline>,
     children: ~[@mut FrameTree],
 }
+// Need to clone the FrameTrees, but _not_ the Pipelines
+impl Clone for FrameTree {
+    fn clone(&self) -> FrameTree {
+        let mut children = ~[];
+        for self.children.iter().advance |&frame_tree| {
+            children.push(@mut (*frame_tree).clone());
+        }
+        FrameTree {
+            pipeline: self.pipeline,
+            parent: self.parent.clone(),
+            children: children,
+        }
+    }
+}
 
 pub struct SendableFrameTree {
     pipeline: Pipeline,
@@ -75,7 +88,7 @@ impl FrameTree {
     /// Returns the frame tree whose key is id
     fn find_mut(@mut self, id: PipelineId) -> Option<@mut FrameTree> {
         if self.pipeline.id == id { return Some(self); }
-        for self.children.mut_iter().advance |frame_tree| {
+        for self.children.iter().advance |frame_tree| {
             let found = frame_tree.find_mut(id);
             if found.is_some() { return found; }
         }
@@ -188,32 +201,28 @@ impl NavigationContext {
         evicted
     }
 
-    /// Returns the frame tree whose key is pipeline_id.
-    pub fn find(&mut self, pipeline_id: PipelineId) -> Option<@mut FrameTree> {
-        for self.current.mut_iter().advance |frame_tree| {
-            let found = frame_tree.find_mut(pipeline_id);
-            if found.is_some() { return found; }
-        }
-        let mut forward =  self.next.mut_rev_iter();
-        let mut backward = self.previous.mut_rev_iter();
-        loop {
-            match (forward.next(), backward.next()) {
-                (None, None) => {
-                    return None;
-                }
-                (next_forward, next_backward) => {
-                    let mut next_forward = next_forward;
-                    let mut next_backward = next_backward;
-                    for next_forward.mut_iter().advance |frame_tree| {
-                        let found = frame_tree.find_mut(pipeline_id);
-                        if found.is_some() { return found; }
-                    }
-                    for next_backward.mut_iter().advance |frame_tree| {
-                        let found = frame_tree.find_mut(pipeline_id);
-                        if found.is_some() { return found; }
-                    }
-                }
-            }
+    /// Returns the frame trees whose keys are pipeline_id.
+    pub fn find_all(&mut self, pipeline_id: PipelineId) -> ~[@mut FrameTree] {
+        let from_current = do self.current.iter().filter_map |frame_tree| {
+            frame_tree.find_mut(pipeline_id)
+        };
+        let from_next =  do self.next.iter().filter_map |frame_tree| {
+            frame_tree.find_mut(pipeline_id)
+        };
+        let from_prev = do self.previous.iter().filter_map |frame_tree| {
+            frame_tree.find_mut(pipeline_id)
+        };
+        from_prev.chain_(from_current).chain_(from_next).collect()
+    }
+
+    pub fn contains(&mut self, pipeline_id: PipelineId) -> bool {
+        let from_current = self.current.iter();
+        let from_next = self.next.iter();
+        let from_prev = self.previous.iter();
+
+        let mut all_contained = from_prev.chain_(from_current).chain_(from_next);
+        do all_contained.any |frame_tree| {
+            frame_tree.contains(pipeline_id)
         }
     }
 }
@@ -269,7 +278,7 @@ impl Constellation {
     /// Helper function for getting a unique pipeline Id
     fn get_next_pipeline_id(&mut self) -> PipelineId {
         let id = self.next_pipeline_id;
-        self.next_pipeline_id = PipelineId(*id + 1);
+        *self.next_pipeline_id += 1;
         id
     }
     
@@ -297,16 +306,17 @@ impl Constellation {
             // This should only be called once per constellation, and only by the browser
             InitLoadUrlMsg(url) => {
                 let pipeline = @mut Pipeline::create(self.get_next_pipeline_id(),
-                                                    self.chan.clone(),
-                                                    self.compositor_chan.clone(),
-                                                    self.image_cache_task.clone(),
-                                                    self.resource_task.clone(),
-                                                    self.profiler_chan.clone(),
-                                                    copy self.opts,
-                                                    {
-                                                        let size = self.compositor_chan.get_size();
-                                                        from_value(Size2D(size.width as uint, size.height as uint))
-                                                    });
+                                                     None,
+                                                     self.chan.clone(),
+                                                     self.compositor_chan.clone(),
+                                                     self.image_cache_task.clone(),
+                                                     self.resource_task.clone(),
+                                                     self.profiler_chan.clone(),
+                                                     copy self.opts,
+                                                     {
+                                                         let size = self.compositor_chan.get_size();
+                                                         from_value(Size2D(size.width as uint, size.height as uint))
+                                                     });
                 if url.path.ends_with(".js") {
                     pipeline.script_chan.send(ExecuteMsg(pipeline.id, url));
                 } else {
@@ -324,35 +334,30 @@ impl Constellation {
                 self.pipelines.insert(pipeline.id, pipeline);
             }
 
-            LoadIframeUrlMsg(url, source_pipeline_id, size_future) => {
+            LoadIframeUrlMsg(url, source_pipeline_id, subpage_id, size_future) => {
                 // A message from the script associated with pipeline_id that it has
                 // parsed an iframe during html parsing. This iframe will result in a
                 // new pipeline being spawned and a frame tree being added to pipeline_id's
                 // frame tree's children. This message is never the result of a link clicked
                 // or a new url entered.
-                //     Start by finding the frame tree matching the pipeline id,
-                // and add the new pipeline to its sub frames. The frame tree
-                // could already be in the navigation context, or it could still
-                // be loading, in which case it is a new id in a constellation.pending_frames
-                // frame change, because pages aren't added to the navi context until they finish
-                // loading (excluding iframes). Which is checked first is seemingly arbitrary
-                let next_pipeline_id = self.get_next_pipeline_id();
-                let frame_tree = {
-                    let frame_tree = self.navigation_context.find(source_pipeline_id);
-                    match frame_tree {
-                        Some(frame_tree) => frame_tree,
-                        None => {
-                            let frame_change = do self.pending_frames.mut_iter().find_ |frame_change| {
-                                frame_change.after.pipeline.id == source_pipeline_id
-                            };
-                            let frame_change = frame_change.expect("Constellation: source pipeline id
-                                of LoadIframeUrlMsg is not in navigation context nor a pending painter.
-                                This should be impossible.");
-                            frame_change.after
-                        }
-                    }
+                //     Start by finding the frame trees matching the pipeline id,
+                // and add the new pipeline to their sub frames.
+                let frame_trees: ~[@mut FrameTree] = {
+                    let matching_navi_frames = self.navigation_context.find_all(source_pipeline_id);
+                    let matching_pending_frames = do self.pending_frames.iter().filter_map |frame_change| {
+                        frame_change.after.find_mut(source_pipeline_id)
+                    };
+                    matching_navi_frames.iter().transform(|&x| x).chain_(matching_pending_frames).collect()
                 };
 
+                if frame_trees.is_empty() {
+                    fail!("Constellation: source pipeline id of LoadIframeUrlMsg is not in
+                           navigation context, nor is it in a pending frame. This should be
+                           impossible.");
+                }
+
+                let next_pipeline_id = self.get_next_pipeline_id();
+
                 // Compare the pipeline's url to the new url. If the origin is the same,
                 // then reuse the script task in creating the new pipeline
                 let source_pipeline = *self.pipelines.find(&source_pipeline_id).expect("Constellation:
@@ -368,6 +373,7 @@ impl Constellation {
                                        source_url.port == url.port) {
                     // Reuse the script task if same-origin url's
                     Pipeline::with_script(next_pipeline_id,
+                                          Some(subpage_id),
                                           self.chan.clone(),
                                           self.compositor_chan.clone(),
                                           self.image_cache_task.clone(),
@@ -378,6 +384,7 @@ impl Constellation {
                 } else {
                     // Create a new script task if not same-origin url's
                     Pipeline::create(next_pipeline_id,
+                                     Some(subpage_id),
                                      self.chan.clone(),
                                      self.compositor_chan.clone(),
                                      self.image_cache_task.clone(),
@@ -392,11 +399,13 @@ impl Constellation {
                 } else {
                     pipeline.load(url, None);
                 }
-                frame_tree.children.push(@mut FrameTree {
-                    pipeline: pipeline,
-                    parent: Some(source_pipeline),
-                    children: ~[],
-                });
+                for frame_trees.iter().advance |frame_tree| {
+                    frame_tree.children.push(@mut FrameTree {
+                        pipeline: pipeline,
+                        parent: Some(source_pipeline),
+                        children: ~[],
+                    });
+                }
                 self.pipelines.insert(pipeline.id, pipeline);
             }
 
@@ -406,6 +415,11 @@ impl Constellation {
             LoadUrlMsg(source_id, url, size_future) => {
                 debug!("received message to load %s", url::to_str(&url));
                 // Make sure no pending page would be overridden.
+                let source_frame = self.current_frame().get_ref().find_mut(source_id).expect(
+                    "Constellation: received a LoadUrlMsg from a pipeline_id associated
+                    with a pipeline not in the active frame tree. This should be
+                    impossible.");
+
                 for self.pending_frames.iter().advance |frame_change| {
                     let old_id = frame_change.before.expect("Constellation: Received load msg
                         from pipeline, but there is no currently active page. This should
@@ -413,7 +427,7 @@ impl Constellation {
                     let changing_frame = self.current_frame().get_ref().find_mut(old_id).expect("Constellation:
                         Pending change has non-active source pipeline. This should be
                         impossible.");
-                    if changing_frame.contains(source_id) {
+                    if changing_frame.contains(source_id) || source_frame.contains(old_id) {
                         // id that sent load msg is being changed already; abort
                         return true;
                     }
@@ -421,33 +435,25 @@ impl Constellation {
                 // Being here means either there are no pending frames, or none of the pending
                 // changes would be overriden by changing the subframe associated with source_id.
 
+                let parent = source_frame.parent.clone();
+                let subpage_id = source_frame.pipeline.subpage_id.clone();
                 let next_pipeline_id = self.get_next_pipeline_id();
+
                 let pipeline = @mut Pipeline::create(next_pipeline_id,
-                                                    self.chan.clone(),
-                                                    self.compositor_chan.clone(),
-                                                    self.image_cache_task.clone(),
-                                                    self.resource_task.clone(),
-                                                    self.profiler_chan.clone(),
-                                                    copy self.opts,
-                                                    size_future);
+                                                     subpage_id,
+                                                     self.chan.clone(),
+                                                     self.compositor_chan.clone(),
+                                                     self.image_cache_task.clone(),
+                                                     self.resource_task.clone(),
+                                                     self.profiler_chan.clone(),
+                                                     copy self.opts,
+                                                     size_future);
 
                 if url.path.ends_with(".js") {
                     pipeline.script_chan.send(ExecuteMsg(pipeline.id, url));
                 } else {
                     pipeline.load(url, Some(constellation_msg::Load));
 
-                    let parent = if self.current_frame().get_ref().pipeline.id == source_id {
-                        // source_id is the root of the current frame tree; replace whole tree
-                        None
-                    } else {
-                        // id is not the root of the current frame tree, but is in the frame tree;
-                        // replace only the subtree
-                        let source_frame = self.current_frame().get_ref().find_mut(source_id).expect(
-                            "Constellation: received a LoadUrlMsg from a pipeline_id associated
-                            with a pipeline not in the active frame tree. This should be
-                            impossible.");
-                        source_frame.parent
-                    };
                     self.pending_frames.push(FrameChange{
                         before: Some(source_id),
                         after: @mut FrameTree {
@@ -532,7 +538,7 @@ impl Constellation {
                     // Create the next frame tree that will be given to the compositor
                     let next_frame_tree = match to_add.parent {
                         None => to_add, // to_add is the root
-                        Some(_parent) => self.current_frame().get(),
+                        Some(_parent) => @mut (*self.current_frame().get()).clone(),
                     };
 
                     // If there are frames to revoke permission from, do so now.
@@ -613,7 +619,7 @@ impl Constellation {
                 for evicted.iter().advance |frame_tree| {
                     // exit any pipelines that don't exist outside the evicted frame trees
                     for frame_tree.iter().advance |frame| {
-                        if self.navigation_context.find(frame.pipeline.id).is_none() {
+                        if !self.navigation_context.contains(frame.pipeline.id) {
                             frame_tree.pipeline.exit();
                             self.pipelines.remove(&frame_tree.pipeline.id);
                         }
diff --git a/src/components/main/pipeline.rs b/src/components/main/pipeline.rs
index ec17e01ef21..1ea7965b02a 100644
--- a/src/components/main/pipeline.rs
+++ b/src/components/main/pipeline.rs
@@ -11,7 +11,7 @@ use gfx::opts::Opts;
 use layout::layout_task::LayoutTask;
 use script::layout_interface::LayoutChan;
 use script::script_task::{ExecuteMsg, LoadMsg};
-use servo_msg::constellation_msg::{ConstellationChan, NavigationType, PipelineId};
+use servo_msg::constellation_msg::{ConstellationChan, NavigationType, PipelineId, SubpageId};
 use script::script_task::{AttachLayoutMsg, NewLayoutInfo, ScriptTask, ScriptChan};
 use script::script_task;
 use servo_net::image_cache_task::ImageCacheTask;
@@ -25,6 +25,7 @@ use std::comm;
 #[deriving(Clone)]
 pub struct Pipeline {
     id: PipelineId,
+    subpage_id: Option<SubpageId>,
     script_chan: ScriptChan,
     layout_chan: LayoutChan,
     render_chan: RenderChan,
@@ -36,13 +37,14 @@ pub struct Pipeline {
 impl Pipeline {
     /// Starts a render task, layout task, and script task. Returns the channels wrapped in a struct.
     pub fn with_script(id: PipelineId,
-                            constellation_chan: ConstellationChan,
-                            compositor_chan: CompositorChan,
-                            image_cache_task: ImageCacheTask,
-                            profiler_chan: ProfilerChan,
-                            opts: Opts,
-                            script_pipeline: &Pipeline,
-                            size_future: Future<Size2D<uint>>) -> Pipeline {
+                       subpage_id: Option<SubpageId>,
+                       constellation_chan: ConstellationChan,
+                       compositor_chan: CompositorChan,
+                       image_cache_task: ImageCacheTask,
+                       profiler_chan: ProfilerChan,
+                       opts: Opts,
+                       script_pipeline: &Pipeline,
+                       size_future: Future<Size2D<uint>>) -> Pipeline {
         
         let (layout_port, layout_chan) = special_stream!(LayoutChan);
         let (render_port, render_chan) = special_stream!(RenderChan);
@@ -72,6 +74,7 @@ impl Pipeline {
         script_pipeline.script_chan.send(AttachLayoutMsg(new_layout_info));
 
         Pipeline::new(id,
+                      subpage_id,
                       script_pipeline.script_chan.clone(),
                       layout_chan,
                       render_chan)
@@ -79,6 +82,7 @@ impl Pipeline {
     }
 
     pub fn create(id: PipelineId,
+                  subpage_id: Option<SubpageId>,
                   constellation_chan: ConstellationChan,
                   compositor_chan: CompositorChan,
                   image_cache_task: ImageCacheTask,
@@ -117,18 +121,21 @@ impl Pipeline {
                            copy opts,
                            profiler_chan);
         Pipeline::new(id,
+                      subpage_id,
                       script_chan,
                       layout_chan,
                       render_chan)
     }
 
     pub fn new(id: PipelineId,
+               subpage_id: Option<SubpageId>,
                script_chan: ScriptChan,
                layout_chan: LayoutChan,
                render_chan: RenderChan)
                -> Pipeline {
         Pipeline {
             id: id,
+            subpage_id: subpage_id,
             script_chan: script_chan,
             layout_chan: layout_chan,
             render_chan: render_chan,
diff --git a/src/components/msg/constellation_msg.rs b/src/components/msg/constellation_msg.rs
index 6f71f8a0454..419aadf1ae3 100644
--- a/src/components/msg/constellation_msg.rs
+++ b/src/components/msg/constellation_msg.rs
@@ -30,7 +30,7 @@ pub enum Msg {
     ExitMsg(Chan<()>),
     InitLoadUrlMsg(Url),
     LoadUrlMsg(PipelineId, Url, Future<Size2D<uint>>),
-    LoadIframeUrlMsg(Url, PipelineId, Future<Size2D<uint>>),
+    LoadIframeUrlMsg(Url, PipelineId, SubpageId, Future<Size2D<uint>>),
     NavigateMsg(NavigationDirection),
     RendererReadyMsg(PipelineId),
     ResizedWindowBroadcast(Size2D<uint>),
@@ -51,3 +51,5 @@ pub enum NavigationDirection {
 
 #[deriving(Clone, Eq, IterBytes)]
 pub struct PipelineId(uint);
+#[deriving(Clone, Eq, IterBytes)]
+pub struct SubpageId(uint);
diff --git a/src/components/script/dom/element.rs b/src/components/script/dom/element.rs
index 7f42230b61b..ac60914db1c 100644
--- a/src/components/script/dom/element.rs
+++ b/src/components/script/dom/element.rs
@@ -18,6 +18,8 @@ use std::str::eq_slice;
 use extra::net::url::Url;
 use geom::size::Size2D;
 
+use servo_msg::constellation_msg::SubpageId;
+
 pub struct Element {
     parent: Node<ScriptView>,
     tag_name: ~str,     // TODO: This should be an atom, not a ~str.
@@ -112,6 +114,7 @@ pub struct HTMLHeadingElement {
 pub struct HTMLIframeElement {
     parent: Element,
     frame: Option<Url>,
+    subpage_id: Option<SubpageId>,
     size_future_chan: Option<ChanOne<Size2D<uint>>>,
 }
 
diff --git a/src/components/script/html/hubbub_html_parser.rs b/src/components/script/html/hubbub_html_parser.rs
index d3b94d2fe3f..8bb6afd22b2 100644
--- a/src/components/script/html/hubbub_html_parser.rs
+++ b/src/components/script/html/hubbub_html_parser.rs
@@ -42,6 +42,7 @@ use std::str::eq_slice;
 use std::result;
 use std::task;
 use hubbub::hubbub;
+use servo_msg::constellation_msg::SubpageId;
 use servo_net::image_cache_task::ImageCacheTask;
 use servo_net::image_cache_task;
 use servo_net::resource_task::{Done, Load, Payload, ResourceTask};
@@ -83,7 +84,7 @@ enum JSMessage {
 pub struct HtmlParserResult {
     root: AbstractNode<ScriptView>,
     style_port: Port<Stylesheet>,
-    iframe_port: Port<(Url, Future<Size2D<uint>>)>,
+    iframe_port: Port<(Url, SubpageId, Future<Size2D<uint>>)>,
     js_port: Port<JSResult>,
 }
 
@@ -222,7 +223,7 @@ fn build_element_from_tag(cx: *JSContext, tag: &str) -> AbstractNode<ScriptView>
     handle_element!(cx, tag, "ul",      HTMLUListElementTypeId, HTMLUListElement, []);
 
     handle_element!(cx, tag, "img", HTMLImageElementTypeId, HTMLImageElement, [(image: None)]);
-    handle_element!(cx, tag, "iframe",  HTMLIframeElementTypeId, HTMLIframeElement, [(frame: None), (size_future_chan: None)]);
+    handle_element!(cx, tag, "iframe",  HTMLIframeElementTypeId, HTMLIframeElement, [(frame: None), (size_future_chan: None), (subpage_id: None)]);
 
     handle_element!(cx, tag, "h1", HTMLHeadingElementTypeId, HTMLHeadingElement, [(level: Heading1)]);
     handle_element!(cx, tag, "h2", HTMLHeadingElementTypeId, HTMLHeadingElement, [(level: Heading2)]);
@@ -240,7 +241,8 @@ fn build_element_from_tag(cx: *JSContext, tag: &str) -> AbstractNode<ScriptView>
 pub fn parse_html(cx: *JSContext,
                   url: Url,
                   resource_task: ResourceTask,
-                  image_cache_task: ImageCacheTask) -> HtmlParserResult {
+                  image_cache_task: ImageCacheTask,
+                  next_subpage_id: SubpageId) -> HtmlParserResult {
     debug!("Hubbub: parsing %?", url);
     // Spawn a CSS parser to receive links to CSS style sheets.
     let resource_task2 = resource_task.clone();
@@ -281,6 +283,8 @@ pub fn parse_html(cx: *JSContext,
 
     let (css_chan2, css_chan3, js_chan2) = (css_chan.clone(), css_chan.clone(), js_chan.clone());
     let (iframe_port, iframe_chan) = comm::stream();
+    let next_subpage_id = Cell::new(next_subpage_id);
+    
     parser.set_tree_handler(~hubbub::TreeHandler {
         create_comment: |data: ~str| {
             debug!("create comment");
@@ -337,10 +341,18 @@ pub fn parse_html(cx: *JSContext,
                         for src_opt.iter().advance |src| {
                             let iframe_url = make_url(src.clone(), Some(url2.clone()));
                             iframe_element.frame = Some(iframe_url.clone());
+                            
+                            // Size future
                             let (port, chan) = comm::oneshot();
                             iframe_element.size_future_chan = Some(chan);
                             let size_future = from_port(port);
-                            iframe_chan.send((iframe_url, size_future));
+
+                            // Subpage Id
+                            let subpage_id = next_subpage_id.take();
+                            iframe_element.subpage_id = Some(subpage_id);
+                            next_subpage_id.put_back(SubpageId(*subpage_id + 1));
+
+                            iframe_chan.send((iframe_url, subpage_id, size_future));
                         }
                     }
                 }
diff --git a/src/components/script/script_task.rs b/src/components/script/script_task.rs
index d5ba18b4402..f769e4b282a 100644
--- a/src/components/script/script_task.rs
+++ b/src/components/script/script_task.rs
@@ -21,7 +21,7 @@ use layout_interface::{ReflowDocumentDamage, ReflowForDisplay, ReflowGoal};
 use layout_interface::ReflowMsg;
 use layout_interface;
 use servo_msg::constellation_msg::{ConstellationChan, LoadUrlMsg, NavigationDirection};
-use servo_msg::constellation_msg::{PipelineId, RendererReadyMsg, ResizedWindowBroadcast};
+use servo_msg::constellation_msg::{PipelineId, SubpageId, RendererReadyMsg, ResizedWindowBroadcast};
 use servo_msg::constellation_msg::{LoadIframeUrlMsg};
 use servo_msg::constellation_msg;
 
@@ -128,6 +128,8 @@ pub struct Page {
     /// and simply caches pages forever (!). The bool indicates if reflow is required
     /// when reloading.
     url: Option<(Url, bool)>,
+
+    next_subpage_id: SubpageId,
 }
 
 pub struct PageTree {
@@ -151,6 +153,7 @@ impl PageTree {
                 window_size: size_future,
                 js_info: None,
                 url: None,
+                next_subpage_id: SubpageId(0),
             },
             inner: ~[],
         }
@@ -599,7 +602,8 @@ impl ScriptTask {
         let html_parsing_result = hubbub_html_parser::parse_html(page.js_info.get_ref().js_compartment.cx.ptr,
                                                                  url.clone(),
                                                                  self.resource_task.clone(),
-                                                                 self.image_cache_task.clone());
+                                                                 self.image_cache_task.clone(),
+                                                                 page.next_subpage_id.clone());
 
         let HtmlParserResult {root, js_port, style_port, iframe_port} = html_parsing_result;
 
@@ -624,12 +628,14 @@ impl ScriptTask {
         // FIXME: These should be streamed to layout as they're parsed. We don't need to stop here
         // in the script task.
 
-        let get_iframes = |iframe_port: &Port<(Url, Future<Size2D<uint>>)>| loop {
+        let get_iframes = |iframe_port: &Port<(Url, SubpageId, Future<Size2D<uint>>)>| loop {
             match iframe_port.try_recv() {
                 None => break,
-                Some((iframe_url, size_future)) => {
+                Some((iframe_url, subpage_id, size_future)) => {
+                    page.next_subpage_id = SubpageId(*subpage_id + 1);
                     self.constellation_chan.send(LoadIframeUrlMsg(iframe_url,
                                                                   pipeline_id,
+                                                                  subpage_id,
                                                                   size_future));
                 }
             }
@@ -652,9 +658,11 @@ impl ScriptTask {
                 Left(Some(sheet)) => {
                     page.layout_chan.send(AddStylesheetMsg(sheet));
                 }
-                Right(Some((iframe_url, size_future))) => {
+                Right(Some((iframe_url, subpage_id, size_future))) => {
+                    page.next_subpage_id = SubpageId(*subpage_id + 1);
                     self.constellation_chan.send(LoadIframeUrlMsg(iframe_url,
                                                                   pipeline_id,
+                                                                  subpage_id,
                                                                   size_future));
                 }
                 Right(None) => {