ActiveX focus question?

When we switch to another html file, the game in the old html will not excute any more; but my question is this, If we have a input textbox in the same html file with unity3d viewer. when we input text, then the w/s/a/d still make the 3D scene move. What I want is to make the 3D don't excute when I make the focus on textbox by the side or do something else. How to control focuse on or off on viewer in the same html file