There seems to be megabytes of difference between 4.7.3 and 4.7.4 for Qt as
distributed by Smart Installer

Like 5.8Mb vs 7.7.Mb for Qt. That is huge for supposedly minor release, what's up with that?

While I've got your ear, does the following ring a bell?

Looks like something broke split screen virtual keyboard support hack that worked Ok before. Not sure if it is Qt version, or something else.
This no longer seems to work reliably on C7 running Anna.

Btw.
http://qt.gitorious.org/qt/pages/QtKnownIssues
is not updated since Qt 4.7.2