Modifier key (ctrl alt shift) is / was pressed?

This question is in the context of:
https://www.emeditor.com/forums/topic/active-string-add-control-modifier/
Yutaka suggested to do this with a macro.

I.e. run a macro when a mouse clicks on an active string, e.g. URI / URL, and check whether a modifier key is pressed / was pressed when clicking on the active string.

I couldn`t find any EmEditor specific way to do this in the documentation.

Typically Javascript couples the modifier key query to an event object (MouseEvent).
E.g. something like macro_event.ctrlKey, macro_event.altKey and macro_event.shiftKey

I also tried the doing this with the Windows Script Host.
Visual basic allows querying with My.Computer.Keyboard.CtrlKeyDown / AltKeyDown / ShiftKeyDown, but there doesn`t seem to be an equivalent Windows Script Host implementation.

Resorting to an external code (e.g. AutoHotKey, Powershell with C#, …) is something I`d like to avoid as the Macro should run reasonably smoothly.

→ Any hints?