GTK4

Note:
    - This is the guides for Windows machine using Windows Subsystem for Linux (WSL).
    - [W]: The action will be performed on Windows Machine.
    - [U]: The action will be performed on WSL (in my case, it named "Ubuntu") on the host Windows Machine.
    - (Guides: ...): The reference link that I refer the step.
    - (Not try yet): This is referred from the guides but I was not in that case, so that I could not try.

-------------------------------
A. Installing from packages
-------------------------------
1. [L] Install required packages.
    1.1. [L] Debian/Ubuntu: sudo apt install libgtk-4-1 libgtk-4-dev gtk-4-examples

2. [L] Verify installation.
    2.1. [L] gtk version - Run: pkg-config --modversion gtk4
    2.2. [L] examples - Run: gtk4-demo

-------------------------------
B. (Optional) Build from Source
-------------------------------
1. [L] Install build tools.
    1.1. [L] sudo apt install build-essential meson ninja-build \
               libglib2.0-dev libpango1.0-dev libgdk-pixbuf-2.0-dev \
               libatk1.0-dev libepoxy-dev libgirepository1.0-dev

2. [L] Clone GTK source.
    2.1. [L] git clone https://gitlab.gnome.org/GNOME/gtk.git
    2.2. [L] cd gtk

3. [L] Build with Meson + Ninja.
    3.1. [L] meson setup builddir
    3.2. [L] ninja -C builddir

4. [L] (Optional) Install system-wide.
    4.1. [L] sudo ninja -C builddir install

#include <gtk/gtk.h>

static void
print_hello (GtkWidget *widget,
             gpointer   data)
{
  g_print ("Hello World\n");
}

static void
activate (GtkApplication *app,
          gpointer        user_data)
{
  GtkWidget *window;
  GtkWidget *button;

  window = gtk_application_window_new (app);
  gtk_window_set_title (GTK_WINDOW (window), "Hello");
  gtk_window_set_default_size (GTK_WINDOW (window), 200, 200);

  button = gtk_button_new_with_label ("Hello World");
  g_signal_connect (button, "clicked", G_CALLBACK (print_hello), NULL);
  gtk_window_set_child (GTK_WINDOW (window), button);

  gtk_window_present (GTK_WINDOW (window));
}

int
main (int    argc,
      char **argv)
{
  GtkApplication *app;
  int status;

  app = gtk_application_new ("org.gtk.example", G_APPLICATION_DEFAULT_FLAGS);
  g_signal_connect (app, "activate", G_CALLBACK (activate), NULL);
  status = g_application_run (G_APPLICATION (app), argc, argv);
  g_object_unref (app);

  return status;
}

mkdir hello-world-project
cd hello-world-project
touch hello-world-gtk4.c
vi hello-world-gtk4.c
...
:wq

gcc $(pkg-config --cflags gtk4) hello-world-gtk4.c -o hell-world-gtk4 $(pkg-config --libs gtk4)

./hello-world-gtk4