Prevent Right clicking on node from Left palette

using Page Flow(http://gojs.net/latest/samples/pageFlow.html) i have some nodes.
for some nodes i have Right-click enabled option.
Left side Panel i don’t need right-click option for whole palette/Node.
but,if i drag and drop from Left side Palette to Right Side, at that time i need to enable right click option for nodes.

FYI:
for right clicking the node, i used contextmenu.(http://gojs.net/latest/samples/customContextMenu.html#)