Mouse origin in Drag Image

How does one define the origin of the Drag Image vs. Mouse position?

Let’s say I created a drag Image of size 1000x300 and i want the mouse to be at position 700,150 when it is dragged. So basically, the dragged image would be 700 pixels left from the mouse x pos and 150 pixels above (=less than) the mouse y pos.

I looked at the juce_ListBox.cpp, because there the listbox’s row the user clicked on is always nice in the center of the mouse (even if multiple rows are selected), but I could not find out why.