[Qt-interest] porting from qt3 to 4

[Tom Panning]

On Thu, Feb 12, 2009 at 9:36 AM, Puneet Bisht <pbisht at nivio.com> wrote:
> hi all,
> we are facing some problems with qt 3 ,so we decided to port the
> application to qt 4 .
> so we will be great full if you can share your experiences with us or can
> guide us , so that we can port it successfully .

We ported our application to Qt 4, but it took considerable time. The
qt3to4 tool does a lot of the rote stuff for you, but our code still
wouldn't compile. And even after we got it to compile, we had to track
down weird behavior shifts in a lot of places. The big ones were:
* setting the background color of a widget won't do anything unless
you call setAutoFillBackground(true)
* null QStrings and empty QStrings are now "equal"
* some virtual methods are no longer virtual, which can be very
confusing to track down unless you check for it
There were some other things, but these were the ones that came up
more than once and/or created difficult-to-find behavior changes.

Having said that, we feel that moving to Qt 4 was the right move.
Tom