What have I done to Preview in Yosemite? I used to open the annotations toolbar and I could select, for example, the arrow tool. Then I would click from A to B and draw the arrow.

Now when I click the arrow tool it plops an arrow on the screenshot and I have to manually drag both ends.

This seems like extra work compared to the old way, what am I likely to have done to have caused this and what can I do to fix it?
I just tested this. Clicking the Arrow tool does indeed simply add an arrow instead of having you drag it out first.

I rarely if ever use the Annotate toolbar, so I am certain I have not made any changes that would have caused this. More likely, the upgrade to Yosemite changed how this tool works.