When the Activate window masking option is selected in Options tab of a Window properties it prevents SSOWatch from clicking on a link or an HTML button masked on Firefox.
Since Quest Enterprise SSO 8.02, the correction is only activated when there is a non-null DWORD value for AlternateClickMethodForWindowMasking registry value in HKEY_LOCAL_MACHINE/SOFTWARE/Enatel/SSOWatch/CommonConfig registry key.
This solution does not work in all cases, in particular when Firefox uses a proxy requiring an authentication.
In such a case, try to validate the page by a method different from a click. For example, send the Enter key to the window or send one or more Tabulation keys to set focus on the requested element and Space character (or Enter) to activate the element.