[palosanto]

I'll see if I can reproduce any issues with text annotations while zoomed in. 

As far as the sizing, I think the main thing I'm worried about is a scenario like this: You have a file at a lower resolution, say 300x200, and the tablet screen is 1200x800 (just to make the math easier). So the file will be increased in size by 400% to fit the screen. If all tool settings are relative to the raw PDF page size (300x200 in this case), a size 20 highlighter would be 20 pixels high in that file, which would show up as 80 pixels tall on the screen. If you then opened a file that is 600x400, and used the same highlighter, it would show up as 40 pixels tall on the screen because the file was only increased in size by 200%. Both files looked like they were the same size on the screen, but due to one file being lower resolution, the highlighter will appear to be a very different size than when used on the higher resolution file. I can only see this confusing users who may not realize that the resolution of the images in the files would play such a big part in how the annotation sizes will be determined. I just don't see how I can support both having the tools be a consistent size with different resolution files, but also be sized correctly regardless of how the page is scaled when the annotation is created. I really need to hear more feedback from users to know how they expect things to behave and which one is more important - having the tool sizes be consistent regardless of image size/resolution, or ensuring that annotations created with a certain size tool will be consistent with other annotations created with that same size regardless of the page scaling/tablet orientation, even if it means that the tool settings will potentially look different with every file that is used.

One thing I could do (although it will add some complexity in determining how to calculate sizes for annotations), is to give the user the ability to control whether the tool sizes are based on the screen resolution or the file resolution. If the sizes are based on the screen resolution, then you would have consistent tool sizes regardless of resolution, which makes it easy to use the same tool settings for all files. If the sizes are based on the file resolution, then you can zoom in/out as needed before annotating, rotate the tablet, etc, and the annotations will all be sized the same regardless of the page scaling. You just may then run into issues with inconsistent tool sizes when switching between files with different image resolutions. For users that like to rotate their tablet a lot and change the zoom level outside the annotation mode, basing the tool sizes on the file resolution would be a better option, especially if they ensure that their files all use images of identical or similar resolutions.

Thanks,
Mike

As far as I'm concerned the method that you are using now creates the most problems of inconsistency in screen size working in one file when creating new text, shape outlines, free form, stamps, etc at different zoom levels with the same selected tool size. We discussed exactly that recently.
So the alternate method (explained in your quotation in your above post #164) would make more sense to me even if the tool sizes display differently in different files unless you can figure out a way to save the tool sizes along with each file for the next time that I open that file or adjust automatically the last tool sizes used when opening a new score in function of its different resolution even the internal size becomes different that the previous one.
You mentioned that the raw pdf internal registered size would be different but the nominal size could be the same across files?  Or do I have all this mixed up?  
Again in any case my vote is for consistency in display while creating new content at different zoom levels or rotating screens at least within the same file.
Juan