Support for the RENDER extension was added to NX starting from the 1.3.0. NX users can enjoy the effects of font anti-aliasing and alpha-blended images, while NX system administrators have the opportunity to reduce the administration overhead caused by the need for having X core fonts loaded on the client machine.

NOTE: In version 4 it won't be necessary to set RENDER or disable it.

Although a centralized X Font Server could have potentially alleviated such hassles, the RENDER extension and the fontconfig tools that are part of any recent Linux distribution, get rid of the problem completely. When using the RENDER extension, in fact, the NX server will make use of any font that is available on the remote side, wihout the need for the same font installed on the client.

Minor problems can be still present, especially when running applications which make heavy use of the graphical effects provided by the new drawing primitives. X applications are usually designed to leverage the X server's extensions and use appropriate fall-backs when they are not. 

More recently, problems of missing text on Ubuntu 12.10 have been reported, and the solution was to disable the RENDER extension in the NX Client GUI.

Disabling the RENDER extension should not cause any functional problem, although users may notice a decreased quality of the display output.

How to disable the RENDER extension

• Launch NX Client,  the Login dialog appears.
• From the select box of the Login dialog choose the session you want to configure.
• Click on the Configure button to open the NX Client GUI.
• In the General tab of the GUI, select the Use custom settings check box,  then click on the Settings button: the Unix - Display settings dialog appears.
• In the new dialog choose the Performace option: Disable the render extension.
• Click on the Ok button to return to the main GUI window.
• Click on the Save button to save your changes and return to the Login dialog.

NX system administrators can optionally disable the extension by adding the option '-norender' to the AgentExtraOptions key, in the node.cfg file on the server.