Add a User-Defined Layout Grid
Thanks for the details!
Marcin Hysz commented
It would be nice to have that. It would be also useful to specify that for example every tenth line is thicker. I can also imagine applying multiple grids for one screen or specifying that the grid should follow a pattern, for example: three lines with 10px spacing then two with 5px then again three with 10px and so on.
David Bey commented
Add "Settings" as a menu item.
User click on "Settings" to reveal a list of items:
User select "Grid". Grid palette appears.
User types in the number of pixels.
 PX x  PX.
User chooses the color of the grid.
User clicks "Save" to save changes.
User clicks "Cancel" to disregards changes.
Visual mockup of grid:
This coulp a way from divshot :