为什么Swing不发布对原始X Server的关注

Question

I noticed that swing application behaves differently. I use Centos 6.5 and I start only raw X server without window manager. In this scenerio, keyboard focus depends on pointer posiotion. Window has keyboard focus if pointer is on it. I tested it on xterm, gnomer-terminal, gedit, firefox.

I developed very simple swing application:

                JFrame jFrame = new JFrame("JFrame tittle");
                JPanel p = new JPanel();

                JTextField textField = new JTextField("111111111111111");

                p.add(textField);
                jFrame.setContentPane(p);
                jFrame.pack();
                jFrame.setVisible(true);

If I run this application then JTextField has focus and I can't change focus to another window. When I move pointer on gnome-terminal JTextField has still keyboard focus and I can use keyboard only on it. I can open menu in gnome-terminal using pointer and menu has keyboard focus then (I can use arrow on menu) but when I close menu, focus returns to JTextField.

In short I can not use any another application. Why? What differs swing application from another? Why swing does not release focus when I move pointer on another window? EDIT: I also clicked on another window of course.

If I start window manager ( metacity ) then it works properly.

=====EDIT==== Picture 1 shows two window: xterm and gnome-terminal. When I move cursor on gnome-terminal then I can use keyboard to write in gnome-terminal, when I move cursor on xterm then keyboard writes to xterm.

When I start my java swing application it appears in left top corner. I can only write into JTextField and cursor does not impact on keyboard focus.Following picture shows it:

I added printing of Look and Feel name and description to swing application so It is printed in console. It is irrelevant.

=====EDIT=====

I found following quote int this tutorial:

Unlike citizens, the window manager has rights but not responsibilities. Programs must be prepared to cooperate with any type of window manager or with none at all […]. — Xlib Programming Manual §1.2.3

So I think that Swing application should be prepared to work without WM.

Answer 1

As i already wrote in the comments, it may be a problem when not using a WindowManager.

see:

There is no foolproof way, across all platforms, to ensure that a window gains the focus. On some operating systems, such as Microsoft Windows, the front window usually becomes the focused window. In these cases, the Window.toFront method moves the window to the front, thereby giving it the focus. However, on other operating systems, such as Solaris™ Operating System, the window manager may choose the focused window based on cursor position, and in these cases the behavior of the Window.toFront method is different.

from here: http://docs.oracle.com/javase/tutorial/uiswing/misc/focus.html