This problem has been around for a long time (and versions). On Macs, when you grab the right side frame (I think it also happens with the left one) of a window to resize it, when you release the mouse and move it SublimeText sees it pressed and starts selecting text while you move the mouse inside the just resized window… To stop this from happening you have to wait (seconds) for the mouse down event to be forgotten and then you can move the mouse without it being dragged and selecting text in your document.
