How to use separate threads for pushbuttons in QT (like SwingWorker in Java)

[artt]

"terminate called after throwing an instance of 'std::bad_alloc'
what(): std::bad_alloc
terminate called recursively..."
if I put connect before start of thread (I need click button twice so it incorrect in principle as it was without nested concnet())
Anyway as in other way. there is bad_alloc, despite I put Lister::listed2 on heap memory: bad_alloc is when I put in the end
delete Lister::listed2; I need probably uqual it to Null. But in my first variant-- evrything works fine despite temporal freezing.
But after 2-3 minutes the whole buncg of xml from WINDOWS folder is shown in textview.