The preventDefault attribute of rich:hotKey has known limitation: it can't prevent native browser actions for selected key-strokes.

Using there key-strokes can cause opening browser menus, popups, etc.

Unfortunately these limitations can't be addressed because lack of support from side of respective browser implementations.

Listing

This page lists these known key-strokes which can produce native browser response, therefore you should avoid using these key-strokes:

• Alt+X
  • Internet Explorer 9 - opens browser's popup
• Ctrl+W
  • Google Chrome 17, Internet Explorer 9 - closes tab