The security warning uses triangle icons to represent itself on the screen. As of now (see 6749517 and 6693253), the warning uses 16x16 icons. There are two problems with them:
1. The icons themselves look somewhat ugly.
2. There's only one size of the icon in the AWT library which brings problems when resizing the icon (since the AWT uses the size of the system window controls - close, maximize buttons, etc. - to set the size of the security warning).