Drag&Drop Memory leak

I found a memory leak in the Drad&Drop system with Qt,

In my sample (see attachement), i've made a bidirectional wrapper to allow the drag&drop of directories from the JS side.

For my test I've dropped some large files (~300Mo). 

Without a.exec(), it's possible to drop many times the file, the JS Garbage Collector do it's job,

With a.exec() uncommented, the used memory keep growing after each drop.