Running Xamarin GTK# application on Linux with multiple windows

LaunchXamarinGtkOnLinux.md

1. First step read and follow official instruction

   https://docs.microsoft.com/ru-ru/xamarin/xamarin-forms/platform/other/gtk?tabs=windows

2. Second step you must configure your Linux system.

   2.1. Install Mono on Linux (GTK# already included)

   https://www.mono-project.com/download/stable/#download-lin

   2.2. Set up sharing of your application between systems (Win and Linux)

   sudo apt-get install cifs-utils
   sudo mkdir /mnt/myshare
   sudo mount -t cifs //my-windows-computer/myshare /mnt/myshare -o domain=my-windows-domain,username=myalias,uid=$USER,gid=$USER
   # /mnt/myshare should now be mapped
   

   More details you can read there https://github.com/Microsoft/MIEngine/wiki/Offroad-Debugging-of-.NET-Core-on-Linux---OSX-from-Visual-Studio

   2.3. Now you can launch you application in Linux. First, run the application through the terminal to see possible errors:

   cd /mnt/myshare
   mono MyGtkApp.exe
   

   2.4. Most likely you will get an error DllNotFoundException on various native libraries in Mono. In most cases, simple mapping for used dlls in the config file of your GTK project will help you:

   https://www.mono-project.com/docs/advanced/pinvoke/dllnotfoundexception/

   If this does not help, then you should check the mapping in /etc/mono/config and indicate the absolute path to the native libraries in mono.

3. By default, Xamarin does not support working with multiple windows at the same time as WPF, but only navigating within the same form. However, in GTK, this restriction can be circumvented by native constructions of the following:

   var mainPage = new YouPage().CreateContainer();
   var vBox = new VBox(false, 0);
   vBox.PackEnd(mainPage, true, true, 0);
   var window = new Window("Window Title");
   window.Add(vBox);
   window.ShowAll();

   Where YouPage - your ContentPage.

   But keep in mind that with this use you will lose the ability to set Application to your window.

   CreateContainer() extension is designed to substitute an empty Application with your form and there is nothing to be done about it. And you will need to specify a ResourceDictionary for each Page individually.

   It’s also good practice to implement a service for managing your windows with template methods

   ShowWindow<T>() where T: Page, new ()
   CloseWindow<T>() where T: Page

   You will need the CloseWindow method to close the window using your buttons, for example, “Close” or “Cancel”.

   For close window you must call

   window?.Destroy();

4. If you want to display a dialog box in this way, then you will need to decide how to transfer the result of the user's response, because Xamarin Page has no interface for this. A service with template methods is also well suited for this purpose:

   ShowDialog<T>(string title, Window parent) where T: Page, new ()
   CloseDialog<T>(bool isConfirm) where T: Page

   Sample for show dialog window:

   try
   {
       var confirmPage = new T().CreateContainer();
       dialog = new Dialog(title, parent, DialogFlags.Modal);
       dialog.VBox.PackEnd(confirmPage, true, true, 0);
       dialog.ShowAll();
       dialog.Run();
   }
   finally { dialog?.Destroy(); }