Does scrolling the mouse wheel help?
Kinda, if you don't mind inconsistent grid sizes. It's either really small text at normal tile size, or blurred tiles at 2x size while the font is at the intended size.
It'd be fantastic if I can get both my text and graphics to stay within an 8x8 grid - Seems like DF halves font sizes, meaning that a font that is 16x16 at 8pt will be 8x8 (4pt?) in DF. I'm trying to mess with a font in FontForge so that it's double the standard size at 8pt.
EDIT: I'm messing with a font's OS/2 metric information via FontForge, as DF is using that to determine font size and width. But how it's using it is just really, really weird; from what I can tell, if the font uses proportional kerning, it ignores most of the data and uses the Win and Typo ascent and descent offsets. However, if you try using Monotype, it gets a bit wonkier and uses the HHead ascent and descent data to determine horizontal spacing.
...Or something like that? It needs more exploration by someone who's got more experience both in fonts and programming. In the end it's just a pain to make a small-sized font work right with it...
EDIT2: I have more info. From what I can tell, it seems that font rendering size mostly relies on the OS/2 font ascent data, preferably reading the Win data and HHead data (which is meant for Macs). Font descent appears to be automatic when set to 0, but setting it to anything else uses that number. As for line gap data, it is ignored by DF for the most part.
Also, the horizontal line clipping is caused by a character that is used at the beginning of some lines (ex. the worldgen options in the starting menu). So that's more of a bug in the strings department, and not the font/graphics department.
From what I can tell, this occurs through fonts that use an OpenType structure. I've not tried a font that uses a TrueType structure.