Question about behavior of QGraphicsView/QGraphicsScene

Ok, so I got into making this really cheesy simple shooter game right?

Well, when I was trying to create and describe the items I was putting in there, I didn't know how to give them the right dimensions and pen and brush type when I was drawing them; I was having to type in some random numbers and properties, compile it, and then look at it-and remember the difference and input that I gave last time... not a smart building strategy.

So I went on a detour to make a little configurable gui where you could just enter the numbers, and the shape would appear on the screen at the push of a button with the numbers you put in as arguments to the QGraphicsScene::drawRect or drawEllipse. Later I will incorporate better features, like being able to set the pen and brush types and stuff... but for now I hit a question that I want some answers to.

But anyway, now I'm on the detour of the detour. Right now, after making the code compilable and stable and everything, I found that the properties change somehow... You'll just have to see for yourself.

Please, grab the attachment that I left, run it, and when you do, put some small numbers in the spinboxes and create a few objects-you'll notice that the positioning scheme starts and the middle and then deviates when you force it to use a scrollbar! to make it use a scrollbar, put some outrageously large numbers in the spinboxes of the gui, create an object, and then clear it. Reset all the numbers of the spinboxes back to reasonable sizes, and recreate an object-notice that NOW the positioning scheme starts from the upper left corner. It's like once you force the QGraphicsScene to create a scrollbar to show a widget that is when the heck out of view, it changes the positioning scheme of the objects. This makes it difficult for me to describe a QGraphicsItem that I want to add...

Can anyone explain to me what is happening, and why, and what I should do about it?

couldn't get the attachment utility to work right... I think its messed up haha

here's where the zip folder with the project in it is:
http://goaruna.com/crqs