We don't plan to provide an "Ignore"-type button to WebShield anytime soon... The reason is, if you absolutely feel that you want to download the infected file (or you're 100% sure it's a false positive), you can always pause/stop the provider. But as soon as the protection is ON, there should basically be no WRONG answer in the dialog, because 90% of the users simply don't know what it's all about, and they just click a (more or less random) button just to make the noisy dialog go away...
BTW the "Ignore" button in the Standard Shield provider is only available when malware is detected ON WRITE (never ON READ). That is, NO HARM can be done by pressing it, unless you pause/stop the Standard Shield provider, the infected file cannot be opened in any way.
Hope this helps,
Vlk