Extending crosshair arms for partial screenshot on Mac OS I very frequently use Command ⌘+Shift ⇧+Control ⌃+4 to take a partial screenshot and store it in the clipboard.

However, the arms of the crosshair which appears are very short, making it hard to select the right area on the first go, especially when I want to select a large area with no border.

So, I'm wondering whether it's possible to extend the arms of that crosshair, perhaps to span the entire screen?
As far as I'm aware, there is no way to manipulate the system crosshair picker, however, Skitch (free!) offers an alternative workflow for partial screenshots. They have a zoomed preview dialog, and the fully extended arms as you desire. Also free in the Mac App Store.