Client-side scripting cannot respond to ActiveView automation events (e.g. Display open events, Display clicks events, etc.). However, client-side scripting can execute public methods and fire events on an ActiveX control.
To get around the issue, you can look into adding client-side scripting on other DOM elements on the HTML page. If you do want to respond to a mouse click on the display, one alternative would be to overlay a transparent element on top of the display that responds to the mouse click events. Can you give us more information on what you are trying to achieve?