I have an scientific application and enabled floating point exceptions. This results in drag&drop operations (at least in my treeview) always giving a floating point invalid-operation exception in line 207 of qtbase/src/gui/kernel/qsimpledrag.cpp. The offending line is:
that is a conversion of floating point +INFINITY to int, which is I believe is Undefined Behaviour.
(grepping out of curiousity shows that the same dubious construct is also used in ./qtquickcontrols/src/controls/qquickmenu.cpp, line 405)