this is an extra subject to vfp but its needed if working with browsers.

i studied the question helped with some web articles and i end with these conclusions:

1.IE11 contextuel menu can extended easily with custom items but this needs to tweak the registry mandatory.
-must create as administrator a new key in registry at HKEY_CURRENT_USER\Software\Microsoft\Internet Explorer\MenuExt\
-must specifythe name and the "contexts" where this new key have action in a REG_DWORD string as follow

the logical OR of the following values:
- Default 0x1, Images 0x2, Controls 0x4, Tables 0x8, Text selection 0x10, Anchor 0x20
must specify the action to execute when clicking the item created(generally execute a local html|html file or a web page.
then can create many items to extend the native IE11 context menu.
this dont override the native IE11 context menu but only extend it.
this section is easy to implement programmatly.
see the attached phtos 1 & 2

2.If use builds a local file or a web page can overide completely the native IE11 context menu and build a custom one on rightclick.
the items must execute local htm-html local files or web pages or even com object (as createObject("visual foxpro.application")).
here must built an html page with javascript scripts.
see the attached photo 3.