How to get the tool window containing another tool window at runtime ?

Finally I found a workaround. In fact OnToolWindowLayoutLoading is useless in my case because it seems the Actipro UI framework has already started to instanciate the tool windows from the layout file when it fires. What I did is to parse the layout file in order to instanciate the tool windows based on the key values found there, and then call LoadToolWindowLayoutFromFile.

The fact that I had not the correct layout (size, containment, etc...) was because I saved the layout too late.

This piece code might help : 

        void restoreLayout() {
            if (System.IO.File.Exists(LayoutFilePath)) {
                XElement layout = XElement.Load(LayoutFilePath);
                layout.Descendants().Where(d => d.Name == "ToolWindow").Count(t => {
                    try {
                        //getToolWindow is to be written (easy)  
                        if(this.mainDockSite.getToolWindow(t.Attribute("Key").Value)==null)
                            //this call instanciates the tool window of custom type ToolWindow based on the key value
                            //in my case I have such a service to open windows from here or there
                            //do what you want  
                            MenuCommandService.invoke(t.Attribute("Key").Value);
                    }
                    catch {
                    }
                    return true;
                });
            }
            try {
                mainDockSite.LoadToolWindowLayoutFromFile(LayoutFilePath);
                //Remove unwanted tool windows instanciated by Actipro Framework if any
                //ToolWindow is the custom type 
                mainDockSite.ToolWindows.OfType<ActiproSoftware.UIStudio.Dock.ToolWindow>().Where(t => !(t is ToolWindow)).ToArray().Count(tw => {
                    tw.Dispose();
                    return true;
                });
            }
            catch {
            }
        }