Use CString .Empty()

Signed-off-by: Sven Strickroth <email@cs-ware.de>
Flash window in order to gain attention

Signed-off-by: Sven Strickroth <email@cs-ware.de>
Use right check for invalid handle

Signed-off-by: Sven Strickroth <email@cs-ware.de>
Drop the superflous statement

The one in else is closer to if, so it is more readable

Signed-off-by: Sup Yut Sum <ch3cooli@gmail.com>