There seems to be bug in the update (version 201) inside the Trimmer. Once I highlight a section of video and click to drag it onto the timeline it starts a new selection instead of dragging the highlighted selection. In other words, I can't drag to the timeline from the trimmer... Does that make sense?
I agree that it starts to create a selection too easily instead of dragging the selection. It seems like the behaviour changes at about 40 degrees from the horizontal. I would change that to something like 20 degrees and perhaps increase the threshold amount of movement a little before Vegas "decides" whether it's going to drag the selection or make a new selection.