Here is a way to make the classic selection box, with marching ants.
It is composed of:
Sprite to mark the corners and hide the ugly overlap if the ants.
Animated sprite of pixel panning over 3 frames center set to the absolute left on every frame.
To get rid of it just destroy the ants and corners when the user does a mouse up, inverted in-touch, or they hit a button. (the 3 scenarios I see the most)
Here is another version that is not as generic as the marching ants one.
This was my first attempt, where I use Corner point sprites, and a background so it registers a collision to what ever you want to select.
I also used a scaled sprite to try and mimic the classic marching ants look. unfortunately it scales and distorts the animations quite a bit.
This is still my favorite version
If you use them in your game please PM the game link to me so I can see them in action 8)