Comment 1 for bug 728598

And for whomever fixes this, a little bit clearer of an explanation:
<christip> lamalex, that's quite odd, I try to explain it to you. You drag & drop a file to the launcher trash icon. The behaviour of the launcher is perfect until you hit the most left pixel of your screen with your pointer. Then the launcher will auto-hide.
<christip> It doesn't matter where you hit the left-most pixel of your screen. Just drag a file to the left-most position and the launcher will hide