Usage

The document must have keyboard focus for #grid to work. You may need to click on the document background or TAB into the page first.

G
Show the grid until you release.
G + H
Show and hold the grid (G will remove it again).
G + F
Toggle the grid to the foreground and back. Pressing F while the grid is held also works.
G + J
Jump to the next grid. Pressing J while the grid is held also works.