Fedora 32 : Can be better? part 016.

Today I tested the Unity 3D version 2020 on Linux Fedora 32.
Maybe it would be better to integrate Unity 3D or Unity Hub in Fedora repo just like other useful software like Blender 3D, GIMP.
It will improve the user experience and attract new users and developers for this distro.
I download the AppImage from Unity website and I run with these commands:

[mythcat@desk Downloads]$ chmod a+x UnityHub.AppImage 
[mythcat@desk Downloads]$ ./UnityHub.AppImage 
r: 0
License accepted
...

Fedora 32 : About positive and negative lookahead with Bash commands.

Today I will talk about something more complex in Linux commands called: positive and negative lookahead.
This solution can be found in several programming languages including Bash
The lookahead process is part of regular expressions.
The lookahead process looks ahead in the string and sees if it matches the given pattern, but then disregard it and move on.
It is very useful when we want to go through the strings.
The lookahead process can be both positive and negative depending on the purpose.
Negative lookahead is indispensable if you want to match something not followed by something else and looks like this:

q(?!s).

The string is the question q is analyzed and if it does not match and is not followed by s returns the result.
The positive lookahead it works the same way only now it is parsed if it corresponds to s.
The positive lookahead looks like this:

q(?=s)

Let's look at a simple example of detecting the PAE option for the processor.
We can use this command but we will find a lot of information ...

[root@desk mythcat]# cat /proc/cpuinfo
processor	: 0
vendor_id	: GenuineIntel
cpu family	: 6
model		: 58
model name	: Intel(R) Celeron(R) CPU G1620 @ 2.70GHz
stepping	: 9
...

In some cases, the resulting information can be taken using pipe and grep but they will be increasingly fragmented.
I will use the same command cpuinfo and we will look for the pae information in the flags.
All CPU flags can be found here.
Let's prove with internal lookahead to find the pae flag.

[root@desk mythcat]# cat /proc/cpuinfo | grep -oP '(?='pae')...' 
pae
pae

This result gives me additional information, namely that there are two cores.
Do you have a question?

Fedora 32 : Visual Code and C# on Fedora distro.

Today I will show you how to use Visual Code with C#.

sudo rpm --import https://packages.microsoft.com/keys/microsoft.asc
sudo sh -c 'echo -e "[code]\nname=Visual Studio Code\nbaseurl=https://packages.microsoft.com/yumrepos/
vscode\nenabled=1\ngpgcheck=1\ngpgkey=https://packages.microsoft.com/keys/microsoft.asc" > 
/etc/yum.repos.d/vscode.repo'

Then use dnf to check and install this editor.

#dnf check-update
#dnf install code

Use Extensions button or Ctrl+Shift+X keys to open in the left side area and intall the C# extension from Microsoft by pressing the Install button, see:

Created a folder named CSharpProjects and using the linux terminal execute the following command:

[mythcat@desk CSharpProjects]$ dotnet new mvc -au None -o aspnetapp
The template "ASP.NET Core Web App (Model-View-Controller)" was created successfully.
This template contains technologies from parties other than Microsoft, 
see https://aka.ms/aspnetcore/3.1-third-party-notices for details.

Processing post-creation actions...
Running 'dotnet restore' on aspnetapp/aspnetapp.csproj...
  Restore completed in 112.76 ms for /home/mythcat/CSharpProjects/aspnetapp/aspnetapp.csproj.

Restore succeeded.

[mythcat@desk CSharpProjects]$ cd aspnetapp/
[mythcat@desk aspnetapp]$ code .

This command will open the Visual Code. At this point, in the aspnetapp folder is an ASP.NET project open in Visual Code. You can run this project with command:

[mythcat@desk aspnetapp]$ dotnet run
warn: Microsoft.AspNetCore.DataProtection.KeyManagement.XmlKeyManager[35]
      No XML encryptor configured. Key {4c284989-9a5d-4ea7-89e2-a383828fd7ab} may be persisted 
      to storage in unencrypted form.
info: Microsoft.Hosting.Lifetime[0]
      Now listening on: https://localhost:5001
info: Microsoft.Hosting.Lifetime[0]
      Now listening on: http://localhost:5000
info: Microsoft.Hosting.Lifetime[0]
      Application started. Press Ctrl+C to shut down.
info: Microsoft.Hosting.Lifetime[0]
      Hosting environment: Development
info: Microsoft.Hosting.Lifetime[0]
      Content root path: /home/mythcat/CSharpProjects/aspnetapp

You can open the https://localhost:5001/ and see the default Welcome page from ASP.NET.

Fedora 32 : Create games with Phaser Editor 2D.

Today I install Phaser Editor 2D on Fedora 32, you can download it from the official website. I create an account and I download the archive for Linux. After unarchive I used very simple:

[mythcat@desk ~]$ cd PhaserEditor2D/
[mythcat@desk PhaserEditor2D]$ ls
editor  PhaserEditor2D  README.TXT  templates
[mythcat@desk PhaserEditor2D]$ ./PhaserEditor2D 
Phaser Editor 2D - v3.7.1

=> Running in Free mode (only 70 files per project allowed)
=> Purchase a license: https://gum.co/phasereditor

2020/10/03 16:17:51 Loading workspace at /home/mythcat/PhaserEditor2D_Projects
2020/10/03 16:17:51 Listening at http://127.0.0.1:1959/editor

Play IDE online : https://play.phasereditor2d.com/
Documentation   : https://help.phasereditor2d.com/v3
File bugs/ideas : https://github.com/PhaserEditor2D/PhaserEditor2D-v3/
Keep in contact : https://twitter.com/PhaserEditor2D

=> Open the web browser at http://127.0.0.1:1959/editor

2020/10/03 16:17:52 No updates available.

Phaser Editor 2D is a commercial IDE to develop video-games. It is delivered as an offline product and users can run it for free (with certain limitations) or can purchase a license key to unlock all features. Phaser Editor 2D version 3, the latest, is a complete new software based on web technologies. So we created Play Phaser Editor 2D, a small service to allow Phaser Editor 2D license owners, to run the editor and create small projects in the cloud. However, in the future, we will provide a different cloud service with options for storage, collaboration, publishing, integration with other services and payment. These are the Play Phaser Editor 2D available plans: Free Plan and Premium Plan About Free Plan: Running the FREE PLAN 0B/50MB of storage is used 59 days before expiration date The Premium Plan comes with these options:

• One Year License - 30$ Valid for one year after the purchase. Phaser Editor 2D Team email support. Write to developers@phasereditor2d.com. The option to refund in the first month after the purchase.
• Two Years License - 45$ Valid for two years after the purchase. Phaser Editor 2D Team email support. Write to developers@phasereditor2d.com. The option to refund in the first month after the purchase.
• Lifetime License - 75$ Never expires. Phaser Editor 2D Team email support. Write to developers@phasereditor2d.com. The option to refund in the first month after the purchase.
• Two Years Team License - 125$ 5 developers allowed. Valid for two years. Phaser Editor 2D Team email support. Write to developers@phasereditor2d.com. The option to refund in the first month after the purchase.

This is a video tutorial from official youtube channel:

Fedora 32 : Can be better? part 015.

In the evening I can spend my time with Fedora 32.

In the last few days I studied GTK # a bit.

I thought it would be useful for Linux users and those who use the language of the FASM assembler to have an editor.

Tonight I created this simple project this simple project named fasm_editor.

The objectives of this project are:

• creating a functional editor;
• implementation of running and compilation requirements;
• settings specific to the Linux operating system;

I believe that this way Fedora Linux can be improved and become better.

Fedora 32 : Can be better? part 014.

The GTK documentation for C # is not very up to date, I tried to use a button to change a label and I failed first time. The Fedora team could improve this to develop the development side. Here's what I've managed to do so far with GTK.

I fixed the source code with this, but I would have preferred a better method:

my_Button.Clicked += delegate {
my_Label.Text = "Use delegate!";
};

Mono is a free and open source implementation of the .NET Framework.

The most popular build tool for Mono is NAnt.

NUnit is very useful for test driven development.

[root@desk mythcat]# dnf install mono-devel
Last metadata expiration check: 0:15:26 ago on Wed 30 Sep 2020 09:04:30 PM EEST.
Package mono-devel-6.6.0-8.fc32.x86_64 is already installed.
Dependencies resolved.
Nothing to do.
Complete!
[root@desk mythcat]# dnf install nant
...
Installed:
  log4net-2.0.8-10.fc32.x86_64            nant-1:0.92-25.fc32.x86_64           
  nunit2-2.6.4-24.fc32.x86_64            

Complete!
[root@desk mythcat]# dnf install nunit nunit-gui
Last metadata expiration check: 0:02:09 ago on Wed 30 Sep 2020 09:27:18 PM EEST.
No match for argument: nunit-gui
Error: Unable to find a match: nunit-gui

Installing MonoDevelop:

[root@desk mythcat]# dnf install monodevelop
...
Installed:
  ORBit2-2.14.19-23.fc32.x86_64                                                 
  gamin-0.1.10-36.fc32.x86_64                                                   
  gnome-desktop-sharp-2.26.0-36.fc31.x86_64                                     
  gnome-sharp-2.24.2-25.fc32.x86_64                                             
  gnome-vfs2-2.24.4-30.fc32.x86_64                                              
  gnome-vfs2-common-2.24.4-30.fc32.noarch                                       
  gtk-sharp2-2.12.45-11.fc32.x86_64                                             
  gtk-sharp2-devel-2.12.45-11.fc32.x86_64                                       
  gtksourceview2-2.11.2-31.fc32.x86_64                                          
  libIDL-0.8.14-21.fc32.x86_64                                                  
  libbonobo-2.32.1-18.fc32.x86_64                                               
  libbonoboui-2.24.5-18.fc32.x86_64                                             
  libgnome-2.32.1-20.fc32.x86_64                                                
  libgnome-keyring-3.12.0-19.fc32.x86_64                                        
  libgnomecanvas-2.30.3-19.fc32.x86_64                                          
  libgnomeui-2.24.5-21.fc32.x86_64                                              
  mono-addins-1.1-13.fc32.x86_64                                                
  monodevelop-5.10.0-17.fc32.x86_64                                             
  vte-0.28.2-31.fc32.x86_64                                                     

Complete!

Install the .NET Core. This is a general-purpose, modular, cross-platform and open-source development Platform.

[root@desk mythcat]# dnf copr enable @dotnet-sig/dotnet
Enabling a Copr repository. Please note that this repository is not part
of the main distribution, and quality may vary.
...
Do you really want to enable copr.fedorainfracloud.org/@dotnet-sig/dotnet? [y/N]: y
Repository successfully enabled.
[root@desk mythcat]# dnf install dotnet
Copr repo for dotnet owned by @dotnet-sig             5.4 kB/s | 3.3 kB     00:00    
Package dotnet-3.1.108-1.fc32.x86_64 is already installed.
Dependencies resolved.
Nothing to do.
Complete! 

Let's start with a GTK project using the MonoDevelop I.D.E.

[mythcat@desk ProjectsCSharp]$ monodevelop 

I use a new solution from .NET with GTK# 2.0 Project template. The default source code is this:

using System;
using Gtk;

namespace MonoDevelopGTK_001
{
	class MainClass
	{
		public static void Main (string[] args)
		{
			Application.Init ();
			MainWindow win = new MainWindow ();
			win.Show ();
			Application.Run ();
		}
	}
}

The result is an simple window form. For a complex form with entry ,label and one button, you can see the next example:

using System;
using Gtk;

namespace MonoDevelopGTK_001
{
	
	class MainClass
	{
		public static void Main (string[] args)
		{
			// define here Entry and Button 
			Entry name;
			Button my_Button;

			Application.Init ();
			MainWindow win = new MainWindow ();
			// change the size of window
			win.SetDefaultSize (640, 480);
			// this will close application
			win.DeleteEvent += new DeleteEventHandler (Window_Delete);

			// use of VBox or HBox
			VBox global_vbox = new VBox();
			win.Add(global_vbox);
			name = new Entry();
			global_vbox.PackStart(name, false, false, 0);
			win.Add(name);

			VBox label_vbox = new VBox();
			global_vbox.Add (label_vbox);
			//Define here a label and put some text in it.
			Label my_Label = new Label();
			my_Label.Text = "Hello World!";
			label_vbox.PackStart(my_Label, false, false, 0);
			//Add the label to the form
			win.Add(my_Label);

			VBox button_vbox = new VBox();
			global_vbox.Add (button_vbox);
			my_Button = new Button("Ok!");
			my_Button.Clicked += OnButtonClicked;
			button_vbox.PackStart(my_Button, false, false, 0);
			win.Add(my_Button);
			// ShowAll is used to see all labels, buttons
			win.ShowAll();
			//win.Show ();
			Application.Run ();

		}

		public static void OnButtonClicked (object obj, EventArgs args)
		{
			//Label my_Label = obj as Gtk.Label;
			Console.WriteLine ("Button Clicked !");

		}

		static void Window_Delete (object obj, DeleteEventArgs args)
		{
			Application.Quit ();
			args.RetVal = true;
		}
	}
}

Fedora 32 : Can be better? part 013.

I would say that I always have a problem with accessing the knowledge base related to errors, errors and configurations in Linux and Fedora distro.

I think it would be very necessary to have as up-to-date documentation as possible in the Fedora distribution system and possibly a database based on questions and answers.

That makes me think of the pilots' manuals ... where all the possible problems are listed.

It would be useful for anyone and especially saves users' memory.

In the age of artificial intelligence, a flow chart for each possible problem generated by Xorg, Network, services that indicate the areas of interaction and possibly the basic checks that a user should make, possible settings depending on the problem or the desired change would be a fantastic map for both a beginner and an advanced user.

After doing some SELinux configurations, my browser did not want to access the internet.

Until the deactivation, the number of SELinux alerts increased dramatically.

The written SELinux policies were not exactly correct.

Obviously I tried to fix the problem by disabling SELinux.

The ping utility sent and received packets to the internet, my browser does not connect to it.

Sometimes a symbolic link or incorrect setting can block your internet access.

I think the problem was generated when disabling SELinux by restarting and shutting down a useful service.

ln -s /run/systemd/resolve/resolv.conf /etc/resolv.conf

Although attention was paid to the possibility of incorrect SELinux settings, a simple check and a restart of the systemd-resolved.service service solved the problem.

[root@desk mythcat]# systemctl status systemd-resolved.service 
● systemd-resolved.service - Network Name Resolution
     Loaded: loaded (/usr/lib/systemd/system/systemd-resolved.service; disabled
     Active: inactive (dead)
       Docs: man:systemd-resolved.service(8)
[root@desk mythcat]# systemctl start systemd-resolved.service 
[root@desk mythcat]# systemctl status systemd-resolved.service
● systemd-resolved.service - Network Name Resolution
     Loaded: loaded (/usr/lib/systemd/system/systemd-resolved.service; disabled
     Active: active (running) since Tue 2020-09-29 22:25:32 EEST; 8s ago

Now I've fixed it.

Fedora 32 : Can be better? part 012.

Pidgin is a chat program that lets you log in to accounts on multiple chat networks simultaneously. 

Pidgin can be installed on multiple operating systems and platforms. 

Pidgin is compatible with the following chat networks out of the box: I.R.C., Jabber/XMPP, Bonjour, Gadu-Gadu, IRC, Novell GroupWise Messenger, Lotus Sametime, SILC, SIMPLE, and Zephyr. Can it be better? 

The only problem a user in need of help may have been in the command line environment. Obviously, in this case, this application cannot be used. I would suggest building a terminal application like WeeChat dedicated to Fedora users and including I.R.C channels. 

Now, let's install this application.

[root@desk mythcat]# dnf install pidgin.x86_64
Last metadata expiration check: 0:45:32 ago on Sun 27 Sep 2020 04:21:51 PM EEST.
Dependencies resolved.
==============================================================================================
 Package                     Architecture    Version                   Repository        Size
==============================================================================================
Installing:
 pidgin                      x86_64          2.13.0-18.fc32            updates          1.4 M
Installing dependencies:
 cyrus-sasl-md5              x86_64          2.1.27-4.fc32             fedora            41 k
 cyrus-sasl-scram            x86_64          2.1.27-4.fc32             fedora            27 k
 farstream02                 x86_64          0.2.9-1.fc32              fedora           239 k
 gtkspell                    x86_64          2.0.16-20.fc32            fedora            43 k
 libgadu                     x86_64          1.12.2-10.fc32            fedora           110 k
 libnice-gstreamer1          x86_64          0.1.17-2.fc32             updates           20 k
 libpurple                   x86_64          2.13.0-18.fc32            updates          5.2 M
 meanwhile                   x86_64          1.1.0-28.fc32             fedora           106 k

Transaction Summary
==============================================================================================
Install  9 Packages

Total download size: 7.2 M
Installed size: 31 M
Is this ok [y/N]: y
Downloading Packages:
...
Complete!

Fedora 32 : Testing the Bookworm software.

The current version of Bookworm (v1.1.2) supports eBooks in the following file formats: EPUB, PDF, MOBI, FB2, CBR, CBZ.

First, I install this software with dnf tool:

[root@desk mythcat]# dnf install bookworm.x86_64 
...
Installed:
  bookworm-1.1.3-0.1.20200414git.c7c3643.fc32.x86_64                                          

Complete!

I tested with some old EPUB and PDF files and I'm not very happy with formatting text on the page.

HI tested with some old EPUB and PDF files and I'm not very happy with the formatting for certain texts on the page, like source code in programming.

Bookworm does one thing and does it well for this simple reader.

You can help this project on GitHub.

Fedora 32 : Can be better? part 011.

Four days ago, the well-known Gnome environment came with a new release.

I guess it will be implemented in Fedora distro soon. 

Fedora 32 : Can be better? part 010.

In this tutorial I will show you how can easy learn with a simple example to have a better Fedora distro with SELinux. 

SELinux uses a policy store to keep track of its loaded policy modules and related settings. 

You can see my active policy store name is MLS.

[root@desk mythcat]# sestatus | grep Loaded
Loaded policy name:             mls

I want to create policy in the most easy way to denny memory. 

I can use many way to do that or find it on SELinux. 

If you want to deny user domains applications to map a memory region as both executable and writable you can use deny_execmem. 

This is dangerous and the executable should be reported in bugzilla and is is enabled by default. 

You must turn on the deny_execmem boolean.

setsebool -P deny_execmem 1

Let's use it:

[root@desk mythcat]# setsebool -P deny_execmem 1
[root@desk mythcat]# ausearch -c 'Web Content' --raw | audit2allow -M my-WebContent
******************** IMPORTANT ***********************
To make this policy package active, execute:

semodule -i my-WebContent.pp

[root@desk mythcat]# semodule -X 300 -i my-WebContent.pp

Let's see if this SELinux is currently loaded:

[root@desk mythcat]# semodule -l | grep Web
my-WebContent

Fedora 32 : Can be better? part 008.

The Fedora development is not very active in the last programming language.
The main reason is the build new packages and put on the repository.
I think this can be improved with a good tool to solve all dependencies and link all into a good package.
Today I tested the new Python version 3.5.10 released on September 5th, 2020.
I download an unzip the archive and I use these commands to build this python version

[mythcat@desk ~]$ cd Python-3.5.10/
[mythcat@desk Python-3.5.10]$ ./configure
checking build system type... x86_64-pc-linux-gnu
checking host system type... x86_64-pc-linux-gnu
checking for python3.5... no
checking for python3... python3
checking for --enable-universalsdk... no
...

The next command is make:

[mythcat@desk Python-3.5.10]$ make
gcc -pthread -c -Wno-unused-result -Wsign-compare -DNDEBUG -g -fwrapv -O3 -Wall -Wstrict-prototypes
   -Werror=declaration-after-statement   -I. -I./Include    -DPy_BUILD_CORE -o Programs/python.o 
./Programs/python.c
...
# On Darwin, always use the python version of the script, the shell
# version doesn't use the compiler customizations that are provided
# in python (_osx_support.py).
if test `uname -s` = Darwin; then \
 cp python-config.py python-config; \
fi

Then I used make test.

[mythcat@desk Python-3.5.10]$ make test
running build
running build_ext
INFO: Can't locate Tcl/Tk libs and/or headers

Python build finished successfully!
...

For the last part I used this command:

[mythcat@desk Python-3.5.10]$ sudo make install
...

The result of this is ...

[mythcat@desk Python-3.5.10]$ ls
aclocal.m4     config.sub    Include          Mac              Modules  platform        python            README
build          configure     install-sh       Makefile         Objects  Programs        Python            setup.py
config.guess   configure.ac  Lib              Makefile.pre     Parser   pybuilddir.txt  python-config     Tools
config.log     Doc           libpython3.5m.a  Makefile.pre.in  PC       pyconfig.h      python-config.py
config.status  Grammar       LICENSE          Misc             PCbuild  pyconfig.h.in   python-gdb.py
[mythcat@desk Python-3.5.10]$ ./python 
Python 3.5.10 (default, Sep  6 2020, 22:32:07) 
[GCC 10.2.1 20200723 (Red Hat 10.2.1-1)] on linux
Type "help", "copyright", "credits" or "license" for more information.
...

Fedora 32 : Can be better? part 009.

The Fedora distro will be better if the development team will come with useful, accurate, and up-to-date information. A very simple example is C and C ++ programming and more precisely how to build programs and packages. Let's take a simple example of creating interfaces with GTK. Let's take a simple example of creating interfaces with GTK that require knowledge of the GCC compiler. First I install gtk3-devel package:

dnf install gtk3-devel 

The Fedora team come with a group install with many feature.

#dnf -y groupinstall "Development Tools"

I test with these examples:

#include 

int main(int   argc,
     char *argv[])
{
  GtkWidget *window;
    
  gtk_init (&argc, &argv);
    
  window = gtk_window_new (GTK_WINDOW_TOPLEVEL);
  gtk_window_set_title (GTK_WINDOW (window), "Hello World");
  gtk_widget_show  (window);
    
  gtk_main ();
    
  return 0;
}

This create a simple window with Hello World title.

#include 

static void on_window_closed(GtkWidget * widget, gpointer data)
{
    gtk_main_quit();
}

int main(int argc, char * argv[])
{
    GtkWidget * window, * label;

    gtk_init(&argc, &argv);

    window = gtk_window_new(GTK_WINDOW_TOPLEVEL);

    g_signal_connect( window, "destroy", G_CALLBACK(on_window_closed), NULL);

    label = gtk_label_new("Hello, World!");

    gtk_container_add(GTK_CONTAINER(window), label);

    gtk_widget_show(label);
    gtk_widget_show(window);

    gtk_main();

    return 0;
}

This is the same example but you will see a label with te text Hello, World!.
The last example is more complex and involves the use of signals attached to the close button and the OK button.
The main window contains three labels with my name and an editbox in which you have to enter my nickname mythcat or something else.

#include 

const char *password = "mythcat";

// close the window application 
void closeApp(GtkWidget *widget, gpointer data)
{
    gtk_main_quit();
}

// show text when you click on button 
void button_clicked(GtkWidget *button, gpointer data)
{
    const char *password_text = gtk_entry_get_text(GTK_ENTRY((GtkWidget *)data));

    if(strcmp(password_text, password) == 0)
        printf("Access granted for user: \"%s\"\n",password);
    else
        printf("Access denied!\n");
 
}

int main( int argc, char *argv[])
{
    GtkWidget *window;
    GtkWidget *label1, *label2, *label3;
    GtkWidget *hbox;
    GtkWidget *vbox;
    GtkWidget *ok_button;
    GtkWidget *password_entry;

    gtk_init(&argc, &argv);

    window = gtk_window_new(GTK_WINDOW_TOPLEVEL);

    gtk_window_set_title(GTK_WINDOW(window), "Labels, password with one button and layout");
    gtk_window_set_position(GTK_WINDOW(window), GTK_WIN_POS_CENTER);
    gtk_window_set_default_size(GTK_WINDOW(window), 300, 200);

    g_signal_connect(G_OBJECT(window), "destroy", G_CALLBACK(closeApp), NULL);

    label1 = gtk_label_new("Catalin");
    label2 = gtk_label_new("George");
    label3 = gtk_label_new("Festila");

    password_entry = gtk_entry_new();
    gtk_entry_set_visibility(GTK_ENTRY(password_entry), FALSE);
    ok_button = gtk_button_new_with_label("OK");
    g_signal_connect(G_OBJECT(ok_button), "clicked", G_CALLBACK(button_clicked),password_entry);

    hbox = gtk_box_new(FALSE, 1);
    vbox = gtk_box_new(TRUE, 2);

    gtk_box_pack_start(GTK_BOX(vbox), label1, TRUE, FALSE, 5);
    gtk_box_pack_start(GTK_BOX(vbox), label2, TRUE, FALSE, 5);
    gtk_box_pack_start(GTK_BOX(hbox), vbox, FALSE, TRUE, 5);
    gtk_box_pack_start(GTK_BOX(hbox), label3, FALSE, FALSE, 5);
    gtk_box_pack_start(GTK_BOX(vbox), ok_button, FALSE, FALSE, 5);
    gtk_box_pack_start(GTK_BOX(hbox), password_entry, TRUE, FALSE, 5);
    gtk_container_add(GTK_CONTAINER(window), hbox);

    gtk_widget_show_all(window);

    gtk_main();

    return 0;
} 

The result can be seen in the following image:

I put the source code for the last example in a test.c file and compiled it like this:

[mythcat@desk ~]$ gcc test.c $(pkg-config --cflags --libs gtk+-3.0) -o test
[mythcat@desk ~]$ ./test