Crash of DiagramScene example

1- create 2 Conditional items
2- create an arrow to linked them
3- select FIRST the arrow and then Conditional items (holding CTRL)
4- delete them
5- the crash happens (dos not appear every time) try again!

remarks:
It's easier to reproduce the crash with 3 items connected each other like a circle. But you have to select the arrows (first?)

Actually, in MainWindow::deleteItem() (mainwindow.cpp line 125 Qt-4.7.0-beta2) you can delete an arrow without to call removeArrow on the both DiagramArrows connected. If you only remove the arrow, DiagramItem(s) still have pointer on an arrow that is not anymore in the scene. I though that it was a memory leak in MainWindow::deleteItem(), because items are removed from scene but nobody delete them... but by this way the arrow pointers of DiagramItems still point on a "almost valid" arrow (not anymore on the scene but happily still in memory). Maybe the best way to correct this problem is to call DiagramItem::removeArrow in the destructor of Arrow(). It does not explain why DiagramScene crashes but it can be a good start.