Thanks for the link. I looked at the documentation and the approach works great when you want to add / remove items unconditionally. The requirement I am trying to implement though is conditional hiding of items. At run time I need to execute a JS function which will hide/show specific menu items, e.g. when the context menu for a document viewer panel opens up.

Is there a way to plug in that conditional logic somewhere?

Or is there a way I can customize the JS code responsible for loading the context menu xml file? This way I could make a runtime decision to use one xml file versus another?

What would you recommend? 

Web Access isn't really intended to be customized at that level. The examples you listed (saving, modifying, adding annotations) are all items that can be controlled through entry access rights. Is there a reason you can't do this through security setups? 

I cannot use the basic access rights as it would affect the regular Laserfiche client.

We're trying to provide a very limited pilot of the Web Access with a lot of restricted functionality - but restricted only on the web access side. So we've modified the Index.aspx with some bootstrapping code in JS that loads our own modules, determines what should be restricted, and loads custom CSS with rules to hide many controls. But we still want the ability for some users (mainly IT) to have unrestricted use of Web Access. The approach is working so far except for the custom menus because they don't have an id or any CSS class allowing them to be targetted with a CSS rule. The alternative approach would be to hook-up into your JS code and wrap some of the functions opening up context menus so we could add our own conditional code there. Are there some specific functions I could take a look at in files like wa90.js? Or is there another way?