The fix for 6633275 (Need to support shaped/translucent windows) uses the libXrender.so library to query whether a given GraphicsConfiguration supports translucency effects. If Java runs on an X11 display that is not configured to use the XRENDER extension, the X server doesn't initialize it, and invoking the XRenderFindVisualFormat() function from the manually loaded libXrender.so library returns NULL. Therefore, the code using this method should carefully test the returned value, and not assume that it is always a valid pointer.