I might be missing something, but I don't see the point of moving the hint somewhere else? It still be the hint poping up.
Btw, in my testing (on Win), the hint does pop up, but as soon as I continue moving the mouse the hint closes and I continue selecting.
In any case, from memory, in ide/sourceeditor.pp should be a hint timer. Which IIRC is used to open the hint. That would have to somehow check, if the mouse button is down....