How would you like the feature to work?

Would like either rulers or guides or both (ideally, with a toggle so they're not always on) and size controls for elements in the theme editor.

Why is this feature important to you?

When I'm creating themes, I'd like certain elements to line up (like title/subtitle placement on two similar slide masters). Would be easy if I could set a guide at, say, 200px from the top to align things on multiple slides, and fields to enter height/width values to make the element size consistent between slides.

Further to this, having broadcast guides for Title Safe and Action Safe would be very handy, to help ensure important information is not cut off by the edges of the screens. Being able to toggle them on like an overlay would be very handy. See attached file for an example, or use DaVinci Resolve, Adobe Premiere Pro, or vMix and turn on their "Safe Area" guides for examples of how other software has implemented them.