public void afterRender() {
            // release the rendering context
            platformCanvas.makeCurrent(NULL);
            try {
                platformCanvas.unlock(); // <- MUST unlock on Linux
            } catch (AWTException e) {
                listener.handleError("Failed to unlock Canvas", e);
            }
        }
Called after <code>beforeRender()</code> to release the threads (unlock); 
so that AWT can update its threads normally.
<p>
<b>NOTE:</b> It is very important to call this method and not leave AWT 
hanging (breaking it) regardless of whether an error occurs during OpenGL
rendering.
jme3-lwjgl3/src/main/java/com/jme3/system/lwjgl/LwjglCanvas.java