I am using PyQt4 and Qt Designer. I have a QListWidget in which I populate after loading a file in my program.
I want to set it so that all items will be checkable, as opposed to just selectable. I have found online that this is a 'flag' of the QListWidget, however, in Qt Designer I can't see where to do this.
Is it possible?
The age-old question. There is an answer here, but I'll try to give some clarification: for several components there isn't enough to set item flag Qt::ItemIsUserCheckable, one needs to set item's check state for the checkbox to appear. Also, there is no widget flag to make all items checkable.
An excerpt from Qt documentation:

Note that checkable items need to be given both a suitable set of
flags and an initial state, indicating whether the item is checked or
not. This is handled automatically for model/view components, but
needs to be explicitly set for instances of QListWidgetItem,
QTableWidgetItem, and QTreeWidgetItem.
Qt Designer QListWidget checkbox