It is not currently possible to change the font size in Text Diff Viewer (Tools / Compare / Text Diff Viewer). I really like the tool (it's better than some other diff viewers I use on text files, and I use it weekly), but the inability to change the font size is a major obstacle. Really need the ability to change the font size, ideally with ctrl-scroll so that it can be done quickly/easily. This will be very useful when switching between different monitors on my my desk, as they have differing sizes and resolutions and so I often need to zoom in or out to see things effectively.
Perhaps this enhancement could be done together with this one, as they are both regarding “ctrl-scroll”: