After downloaded and installed Qt SDK for Windows 4.6.2, the first time, I tried the famous example, fancybrowser, it is no problem to open http://www.google.com/ncr, but when I clicked the Gmail link on the Google home page, I got the following error message,
QSslSocket: cannot call unresolved function SSLv3_client_method
QSslSocket: cannot call unresolved function SSL_CTX_new
QSslSocket: cannot call unresolved function SSL_library_init
QSslSocket: cannot call unresolved function ERR_get_error
QSslSocket: cannot call unresolved function ERR_error_string
After a quick search, I noticed OpenSSL is not installed, so needs an OpenSSL for Windows. I tried Win32 OpenSSL and GnuWin OpenSSL for Windows, both works.
For Win32 OpenSSL, just download Win32 OpenSSL v1.0.0 Light or Win32 OpenSSL v0.9.8n Light(both need Visual C++ 2008 Redistributables), install it(i used Universal Extractor unpack them then copy libeay32.dll and ssleay32.dll to windows system folder). For GnuWin OpenSSL for Windows, just download openssl-0.9.8h-1-bin.zip then extract libeay32.dll and libssl32.dll to windows system folder or mingw bin folder (installed with qt).

P.S.
The OpenSSL Project is a collaborative effort to develop a robust, commercial-grade, full-featured, and Open Source toolkit implementing the Secure Sockets Layer (SSL v2/v3) and Transport Layer Security (TLS v1) protocols as well as a full-strength general purpose cryptography library.

Today I used Gmail as usually, but when I clicked the send button, I got the following alert,

Did you mean to attach files
You wrote "I have attached" in your message, but there are no files attached, Send anyway?

It is really an interesting thing, Gmail can auto check my email, and prevent me from forgetting the attachment.