Begin working on a graphical TextEditor.

It's gonna be a wrapper around a new GTextEditor widget so I can easily
reuse the functionality anywhere I need it. :^)

Applications/TextEditor/main.cpp

@@ -0,0 +1,86 @@
+#include <LibGUI/GWindow.h>
+#include <LibGUI/GWidget.h>
+#include <LibGUI/GBoxLayout.h>
+#include <LibGUI/GApplication.h>
+#include <LibGUI/GStatusBar.h>
+#include <LibGUI/GToolBar.h>
+#include <LibGUI/GMenuBar.h>
+#include <LibGUI/GTextEditor.h>
+#include <LibGUI/GAction.h>
+#include <AK/StringBuilder.h>
+#include <unistd.h>
+#include <stdio.h>
+#include <signal.h>
+#include <fcntl.h>
+
+int main(int argc, char** argv)
+{
+    GApplication app(argc, argv);
+
+    auto* widget = new GWidget;
+    widget->set_fill_with_background_color(false);
+    widget->set_layout(make<GBoxLayout>(Orientation::Vertical));
+
+    auto* toolbar = new GToolBar(widget);
+    auto* text_editor = new GTextEditor(widget);
+    auto* statusbar = new GStatusBar(widget);
+
+    {
+        StringBuilder builder;
+        int fd = open("/home/anon/ReadMe.md", O_RDONLY);
+        if (fd < 0) {
+            perror("open");
+            return 1;
+        }
+        for (;;) {
+            char buffer[BUFSIZ];
+            ssize_t nread = read(fd, buffer, sizeof(buffer));
+            if (nread < 0) {
+                perror("read");
+                return 1;
+            }
+            if (nread == 0)
+                break;
+            builder.append(buffer, nread);
+        }
+
+        int rc = close(fd);
+        if (rc < 0) {
+            perror("close");
+            return 1;
+        }
+
+        text_editor->set_text(builder.to_string());
+    }
+
+    auto menubar = make<GMenuBar>();
+    auto app_menu = make<GMenu>("TextEditor");
+    app_menu->add_action(GAction::create("Quit", { Mod_Alt, Key_F4 }, [] (const GAction&) {
+        GApplication::the().quit(0);
+        return;
+    }));
+    menubar->add_menu(move(app_menu));
+
+    auto file_menu = make<GMenu>("File");
+    menubar->add_menu(move(file_menu));
+
+    auto edit_menu = make<GMenu>("Edit");
+    menubar->add_menu(move(edit_menu));
+
+    auto help_menu = make<GMenu>("Help");
+    help_menu->add_action(GAction::create("About", [] (const GAction&) {
+        dbgprintf("FIXME: Implement Help/About\n");
+    }));
+    menubar->add_menu(move(help_menu));
+
+    app.set_menubar(move(menubar));
+
+    auto* window = new GWindow;
+    window->set_title("TextEditor");
+    window->set_rect(20, 200, 640, 400);
+    window->set_main_widget(widget);
+    window->set_should_exit_app_on_close(true);
+    window->show();
+
+    return app.exec();
+}