LWJGL + Ubuntu = no fullscreen?

Question

Java

The essence of the problem is, the full screen can only be done if it is with the resolution of the monitor itself.

DisplayMode mode = Display.getDesktopDisplayMode();<br/>
Display.setFullscreen(true);<br/>
Display.setDisplayMode(mode);<br/>
Display.create(pf);

But here's to make a full screen with a different resolution

DisplayMode mode = new DisplayMode(800, 600);<br/>
Display.setFullscreen(true);<br/>
Display.setDisplayMode(mode);<br/>
Display.create(pf);

Well, it does not work, maybe someone faced such a problem, tell me how to solve it.
Google search did not help, found one page but did not help.