Glowing edge for blocks player pointing at to indicate it

When players explain something in Minecraft (especially when explaining redstone circuits), it is hard to tell/emphasize the block he/she is pointing at. What they usually do is shaking the camera while recording a video, or punching and placing it back. That's really awkward..

It would be great if the edge of a block would glow (similar to glowing effect) when player is pointing at it while holding a key (G or B or V or C for example). And player could stoke the key repeatedly to make a block blink.

It would be nicer that when holding the key and moving cursor, all the blocks that swept through would have glowing edge. And release the key they will return normal.

This is just an indicator and won't affect gameplay.

(P.S. I did do a search before post it and I couldn't find any related post..Hope there is no duplicated post..)