Increase line height in font waterfall view

[cygnus-glacier]

Is your feature request related to a problem? Please describe.
The waterfall view is very cramped, probably to fit a potentially large number of font sizes. However even when using a limited number of custom sizes (8, 11, 16, 32) to reduce visual clutter there isn't much space between one line and the next and there is some negative space underneath the waterfall list. The lack of space between lines can make it hard to read and study the characters properly.

Describe the solution you'd like
I'd like either for the line height to distribute automatically based on the number of lines in the window or alternatively add an extra option in the waterfall settings to add a custom line height value. I suspect the latter would be the most robust as very large waterfalls will overflow and create a scroll bar.

Describe alternatives you've considered
I could choose a single font size to avoid the cramped lines however it would not be a good fix. The benefit of observing a font at multiple sizes simultaneously is to view features of the font in different contexts - the letters close up can help with font selection, at a print or more regular document size can help you understand how good the font is for paragraph text, or very small - trying to decide when the font becomes illegible.

Additional context
I've added a screenshot showing the Custom Waterfall Settings menu and how this looks in the font viewer.