Could you please tell me steps to follow to create your own custom node...?? or any document which explains this?
Thanks in advance
The examples are in the ui plugin.xml.
You have to implement the 'graphElement' extension point. The 'entry' subelement has the possibility of defining an 'icon' attribute where you simply specify the path to the file where the icon resides.
You should be warned though that these extension points will probably change to offer more flexibility when I will be starting to work on the 3.1 branch of the designer.
i added icon attribute to entry subelement and it worked fine. For developers who wanted to define their own custom nodes should look plugin.xml file of gpd plugin and use extension points koen mentioned. but i advice to directly editing plugin.xml of your plugin for extensions. you can copy necessary parts from the original plugin.xml file of gpd.
in addition you have to write necessary ui classes of your custom nodes. i look at the source code of the gpd from CVS repository and plugin.xml file to write my own ui(user interface) custom nodes.