[Kwintv] crash in QtVision::SetChannel

[Rizsanyi Zsolt]

Hi!

As you maybe already know, there is a bug in QtVision::SetChannel causing a 
crash sometimes.

A backtrace showed the line 505 in qtvision.cpp to have caused the crash. And 
indeed:
void QtVision::setChannel( Channel *channel )
{
    if (!channel)
        return;

    //kdDebug() << "QtVision::setChannel()" << endl;
····
    if (_chan)
      _prevChannel = _chan->number (); // line 505

It assumes, that if _chan is not NULL then it is a valid pointer. Which is not 
a valid assumption, since the channels are deleted by ChannelStore (and in my 
case they were deleted by openChannelFile)

I see some possible solutions to this:
1) remove this previous channel thing - it is only used for dcop if I 
understand it correctly, and I dont see for what it is good for
2) do a copy of the channel when setting _chan (meaning 'if (_chan) delete 
_chan; _chan = new Channel(channel)'  instead of '_chan = channel' ). Of 
course in that case we should take care to delete the Channel objects where 
_chan points to when assigning a new value
It can also cause some problems when checking channel equality, since we now 
have two different objects
3) take care to do '_chan = NULL' when the channel store is deleted (or that 
exact channel is deleted) -- this may be impossible

I vote for solution 1)

What do you vote for? :)

Regards
Zsolt