I received a frantic call from an acquaintance today. She had been happily using the Dynamic Spelling feature in InDesign, when all of a sudden the red underline no longer showed up on her screen, even though she had misspelled words staring her in the face.
Ah! She's accidentally gone into Preview mode (View > Screen Mode > Preview), I thought, but that wasn't the case. After a moment of thought, I asked her to choose View > Overprint Preview and tell me if it was checked. Sure enough it was. This prompted me to write this post.
Both Preview Mode and Overprint Preview do very similar, but slightly different things. Both will hide all non-printing items, including:
Objects designated as non-printing via the Attributes panel
Guides and Grids
XML Tag Markers
But there are four important differences between the two commands:
1. Overprint preview will display objects that have been set to overprint via the Attributes panel as they will appear when offset printed. This overprint attribute is ignored in Preview mode.
2. Overprint preview temporarily displays all page objects in High-Quality Display Mode, similar to choosing View > Display Performance > High Quality Display. Preview mode doesn't change the Display Performance setting.
3. Preview mode hides all objects on the pasteboard with a gray background. Overprint Preview doesn't affect objects on the pasteboard.
4. Preview mode trims all page items that bleed off the page to the trim boundary, Overprint Preview doesn't.
In my humble opinion, Adobe should combine Overprint Preview and Preview Mode into one command. We just need an easy way to get in and out of a "make it look as printed" mode, like Preview Mode, but with the Overprinting and High Quality Display setting.