Grub2 theme bug with relative numeric values for boot_menu?

[John Hupp]

I'm trying to make my theme completely resolution-independent.  You can see a current screen shot at Post your Grub 2 Themes

Grub responded well to % values for the numeric values in the progress bar and labels.  Also OK with %'s for boot_menu properties top, left, height, width.

But I'm getting bad behavior with item_height and the other properties.  For a 1024x768 grub display and an original setting of item_height = 26, I can't get equivalent output unless I set item_height = 27%

So item_height seems to be referencing a parent with a height of about 96, rather than 768.

This is in a VMWare Player environment running Lubuntu 14.04.

Is this a known problem, or is there an explanation/workaround?

(I also realized as I got into this that I will run into a problem with different aspect ratios, so other than creating at least two themes for the commonest aspect ratios, I'd be interested in a tip there as well if there is a solution.)