Hello again @matjaz & @Emmanuel
Interview : Tuukka Rantala, Graphic Designer at Porkka & Kuutsa (Finland) | Pinegrow Web Editor
What features are currently lacking in Pinegrow right now and for which you use other applications (and which applications?)
The most important feature lacking is possibility to use guides and grids (like in Illustrator, Indesign or Photoshop). Sometimes I have used a sheet of white paper as a guide to check that some elements are even on screen.
[….]
The above excerpt from the newly posted article/interview reminded me of my previous post above suggesting to have a simple toggle " grid " overlay/underlay.
Also in regards to draggable etc., " guides " (rulers) there are existing things which may help implementing that if desired also, a few examples are seen below.
- GitHub - mark-rolich/RulersGuides.js: Creates Photoshop-like guides and rulers interface on a web page
- GitHub - MrFrankel/ruler: HTML5 Canvas ruler for authoring tools
- etc.,
Both grids / guides would be better than a user holding a sheet of paper up to the screen as mentioned. 
PS: Their later comment about including other CMS’s reminded me of the discussion of the many Flat File CMS solutions which exist. Most could be implemented with little work for allowing drag and drop much like the newly capable Wordpress Smart Actions, for generating editible regions, etc., for any chosen CMS’s.