This is how I sent the signal

Qt Code: 
  1. wdgt.trvModules->dataChanged(wdgt.trvModules->currentIndex(),wdgt.trvModules->currentIndex());
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I had it right at the end of the method that changes the data. I have also added a call to setData in the same place.

Qt Code: 
  1. wdgt.trvModules->model()->setData(wdgt.trvModules->currentIndex(),classSize);	
  2.  
  3. wdgt.trvModules->dataChanged(wdgt.trvModules->currentIndex(),wdgt.trvModules->currentIndex());
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Where wdgt.trvModules is a pointer to teh QTreeView and I'm changing the selected (singular) item.