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WPF Custom MainWindow using CreateWindowEx()

I was working on a project using WPF, I want to modify the MainWindow to have some extended window styles. I have referred some docs and found out that I can set the window styles using SetWindowLong(), but in my case it will not work because I am trying to use WS_EX_NOREDIRECTIONBITMAP as the extended window style. when I use SetWindowLong() it does nothing. I have read somewhere that WS_EX_NOREDIRECTIONBITMAP can only be set while creating the window. So is there any way that i could modify the CreateWindowEx() of the WPF MainWindow.
I have found another alternate method to achieve this but it is by using the Undocumented API function.(SetWindowCompositionAttribute()). I need my project to be stable so is there any other method to achieve this?
If SetWindowCompositionAttribute() can set WS_EX_NOREDIRECTIONBITMAP at runtime, there must be a workaround to do this.
Here is the screenshot of what i want to achieve :
It is possible to do it in C++ but in C# WPF i haven't found a way to do this.

If you want to set WS_EX_NOREDIRECTIONBITMAP during creating MainWindow then you can create MainWindow manually. Just remove StartupUri from App.xaml and create new event handler for Startup event.
<Application x:Class="WpfApp1.App"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
Startup="App_Startup">
App.xaml.cs
void App_Startup(object sender, StartupEventArgs e)
{
// replace with your code
MainWindow window = new MainWindow();
window.Show();
}
But it would be useful if you can shore more code.

Making a new WPF window from C# class

I currently have one window designed in WPF and coded in C#. I want one of my buttons to open another window, which I would also like to design in WPF. What is the best way for me to do this? Can I make multiple xaml files and call them from the same .cs class? Or should I just have one xaml file? I tried to add a new window into my xaml but it won't allow me to do that. I want all the code to be in the same C# class.

Yes, you can have multiple XAML files and call them from the same .cs file.
For exemple, let's say you have Window1.xaml and Window2.xaml. Window1 is your main window, and the code behind will look like this :
public partial class Window1 : Window
{
public MainWindow()
{
InitializeComponent();
}
}
In Window1 you have a button named btnOpenWindow. On click, you may do that to open Window2 :
private void btnOpenWindow_Click(object sender, RoutedEventArgs e)
{
var window = new Window2();
window.Show();
}
Then a new Window2 is opened.
However you won't be able to get events or others things coming from Window2 in Window1.xaml.cs, obviously you will control that in Window2.xaml.cs for exemple.

You should use the MVVM pattern in your project.
So you have different windows and just one ViewModel to handel these views and your data.
Have a look on: MVVM: Tutorial from start to finish?

Change Startup Window

I am using Visual Studio 2012 C#. I have created a WPF application project with a main window and added a login window to my project. I want to change the startup window to be my login window but can't seem to do so.
I went to the properties but all I see there is Myproject.app - should it not display the forms of my project?
Anyway I have tried running the window from code as well like so :
Application.Run(new Login());
But that does not seem to work. It gives an error saying :
Error 1 An object reference is required for the non-static field, method, or property 'System.Windows.Application.Run(System.Windows.Window)'

To change startup window update App.xaml by changing Application.StartupUri:
<Application ... StartupUri="MainWindow.xaml">

To change the startup window programmatically go to App.xaml
remove the line StartupUri="MainWindow.xaml" (This will remove the default startup window configuration), now add the startup event Startup="Application_Startup", in App.xaml.cs
private void Application_Startup(object sender, StartupEventArgs e)
{
If(somecase)
{
MainWindow mainWindow = new MainWindow ();
mainWindow.Show();
}
else
{
OtherWindow otherWindow= new OtherWindow();
otherWindow.Show();
}
}

use Application.Current.Run Instead of Application.Run

Multiple calls of Application.Run in WPF

I'm trying to run a window, close it, and then run a second window, in a similar way that seems to work with Windows Forms.
namespace WpfApplication1
{
public partial class App : Application
{
[STAThread]
public static void Main()
{
Application app = new Application();
//windowMain.Show();
app.ShutdownMode = ShutdownMode.OnExplicitShutdown;
MainWindow windowMain = new MainWindow();
app.Run(windowMain);
Window1 window1 = new Window1();
window1.Show();
app.Run(window1);
}
}
}
I've set the Build Action in the App.xaml properties from ApplicationDefinition to Page, but the programme throws an exception when window1 is initialised. What am I doing wrong?
Edit: I've modified the xaml in App.xaml as suggested by first answer and edited main as suggested by the comment.
<Application x:Class="WpfApplication1.App"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
StartupUri="MainWindow.xaml"
ShutdownMode="OnExplicitShutdown">
<Application.Resources>
</Application.Resources>
</Application>
but I'm still getting the exception.

OK this is what I've divined so far. The Solution Builder looks for a Main() function. Why its not a WinMain() function I'm still not a hundred per cent clear on. If there is no Main(), you get an error. You can have more than one Main() as long as the Project properties: "Application" page/tab: property: "StartUp Object" is set to point to one of the main()s. This is done from an automatically created drop down list.
When a “WPF Application” project is created, Visual Studio(VS) create an xaml file called “App.xaml”. This is a class declaration where “App” is derived from the “Application” Class. VS also automatically generates hidden files for an xaml file. It creates a “name.g.i.cs” file, when the xaml file is created. It creates a “name.g.cs” file the first time the project is built after the creation of the xaml file. In this case it creates “App.g.cs” and “App.g.i.cs”. These files are hidden by default. To view them, press the “Show all files” button at the top of the Solution Explorer, they can be found in “\ obj\86\Debug” folder. When you delete an xaml file the “name.g.i.cs” and the “name.g.cs” files remain and are not deleted.
The “App.xaml” file’s “build Action” property is set to “Application Definition” when created by VS. When this property is set to “Application Definition” a Main() function is automatically created in “name.g.i.cs”:
[System.STAThreadAttribute()]
[System.Diagnostics.DebuggerNonUserCodeAttribute()]
public static void Main()
{
WpfApplication8.App app = new WpfApplication8.App();
app.InitializeComponent();
app.Run();
}
When this property is set to “Page”, the Main() function is automatically removed by VS. You can create new “Application” derived classes in code or in xaml. I haven’t found a neat way to do it in xaml. There doesn’t seem to be a template for an xaml “Application” derived class. I created a “.cs” code file and then renamed it to an .xaml file. For some reason VS won’t allow you to have more than one xaml “Application” declaration file set to “Application Build”, it doesn’t even give you the option of choosing one in the "Project: Properties: Application": “Startup Object” property.
As you can see in the hidden Main(), an instance of “App” is instantiated and run. If using your own Main() function: an instance of, the base “Application” class, or an “Application” derived class (whether declared in code or in xaml), can be declared and run. The “Application” class should only be instantiated once and should only be run once. If the “Application” derived class is declared in xaml then a simple application can be run by using the StartUpUri property in the xaml file: StartupUri="Windowname.xaml". Alternatively the top level UI programme logic can be placed in a Startup event handler. If “Startup="Application_Startup" is placed in the “App.xaml” file then an event handler can be written:
private void Application_Startup(object sender, StartupEventArgs e)
{
MainWindow windowMain = new MainWindow();
windowMain.ShowDialog();
Window1 window1 = new Window1();
window1.ShowDialog();
Shutdown();
}
You have to use ShowDialog() here, because it blocks until the window is closed. If you used Show() instead, it would show one window, then immediately show the other one and shutdown the application. In this case there's no need to call the Run() method yourself, that's done automatically.
The “Application” class instance can be run in code whether its declared in code or in xaml. You can then perform initialisation code prior to calling Run(). This would be placed in the Application_ Startup() event handler using the other way. However, if the “Application.Run” call is ever made in the programme, then no windows should be opened (using show() or ShowDialog()) in Main() or anywhere outside of the Application Class or within events and functions called from those events, called during “Application.Run()”.
The Application class has a ShutdownMode property (Application.ShutdownMode). The default for this is: “OnMainWindowClose”. This property can also be set to “OnLastWindowClose” or “OnExplicitShutdown” in code or in the xaml. You will need to reset this if you don't want the programme to close down when the MainWindow is closed.
I think for my purposes it is better not to use the Application class at all and just call the windows using Show() and “ShowDialog()”. This way I can use WPF pages but I could also call Windows Forms, or DirectX screens, as long as they are not open at the same time, or have no UI at all, if the programme is running remotely. Is there any reason for not doing it this way?

I think your application is shuting down when you close the first window. You need to set Application.ShutdownMode to OnExplicitShutdown.

If all you want to do is to show one window, when that closes, show another and when that closes, shutdown the whole application, you should keep the Build action as ApplicationDefinition, set ShutdownMode to OnExplicitShutdown (probably in App.xaml, but you can it in code-behind too) and put the following code in an event handler of the Startup event of your application:
private void Application_Startup(object sender, StartupEventArgs e)
{
MainWindow windowMain = new MainWindow();
windowMain.ShowDialog();
Window1 window1 = new Window1();
window1.ShowDialog();
Shutdown();
}
You have to use ShowDialog() here, because it blocks until the window is closed. If you used Show() instead, it would show one window, then immediatelly show the other one and shutdown the application.
There's no need to run the Run() method yourself, that's done automatically.

WPF: Keeping an object running?

I'm having problems understanding how WPF app.xaml works. Is it like Main method in winforms programing?
What I want is a MainController class which keeps track of my Window object. For example:
public MainController()
{
_windowMain = new WindowMain(this);
}
public WindowMain GetWindowMain
{
get { _windowMain; }
}
And so on with all the windows I have in my project. But where should my MainController be initialized?

Check the StartupUri property of the App.xaml file. It links in a Window's XAML file within your project to be launched at startup.
If you want to avoid this, then I believe you can override a method in App.xaml.cs to launch the window explicitly via your controller.
You should understand that the compiler makes a class called 'App' that overrides System.Windows.Application by compiling your App.xaml and App.xaml.cs files. Check the documentation for that class to learn more about the lifecycle management of your WPF application.