Thanks for taking a look. And for the test program. I'll get it compiled and play around with it.
StudioTax is a C# application, although I couldn't get it to run under mono.
Their implementation of this appears to be a winforms control comprised of multiple labels. And they're using the width from the bounding box as the offset for the next label.
I'll try to better understand `StringFormatFlagsLineLimit` and text rendering in general. And see if I can identify a better appoach.