[Qt-interest] Bizarre undefined behaviour with UI generated classes

[John Moran]

Hello,

I've written a class that manages resources (QWidgets that represent
pages of a QStackedWidget, and their associated UI classes) and makes
them pages of a QStackedWidget that it also manages.

I'm experiencing bizarre undefined behaviour:

// client code, within main widget that is the "parent" (not parent,
but parent of its widgets) of the resource managing class:

 mymainscreen.setupUi(this); // mymainscreen is my resource managing
class; Not actually UI generated, but based on a UI generated class


// *Doesn't* appear to be problematic, despite being more or less
identical to code below
mymainscreen.working_page->OtherTree->setSelectionBehavior(QAbstractItemView::SelectRows);

// consistenly causes UB (debugger locks):
    mymainscreen.options_page->SalesTree->setSelectionBehavior(QAbstractItemView::SelectRows);


When I do something that ought to be exactly equivalent to the call to
.options_page->SalesTree->setSelectionBehavior() above within the
resource managing class itself:


// set up options
    options_widget = new QWidget(MainScreen);
    options_page = new Ui::Options;
    options_page->setupUi(options_widget);
    stackedWidget->addWidget(options_widget);

// try and re-create problem here (cannot):

    options_page->SalesTree->setSelectionBehavior(QAbstractItemView::SelectRows);


It works! this, despite the fact that we don't touch the
options_page/SalesTree ptrs again within our resource managing class,
and despite the fact that essentially the same thing consistently
works elsewhere!

What might be in play here? What should I do?

Regards,
John Moran