As you know, Geany can highlight diffs/patch files. The main point of doing this is to make changed lines more visible, outstanding, because they are the important stuff. So yes, highlighting. Dark Fruit Salad and Zenburn are not even trying. But don't take my word for it; take any diff and try them. Both themes do highlighting of added lines poorly, but both fail miserably in case of deleted lines.
I didn't try experimenting with colors yet, but there are themes that I personally feel being particularly good at highlighting diffs, like Tango Light and Kugel (conventional red and green) and Oblivion 2 (unusual green and blue).
You can also say that GitHub theme went wrong with acid green on white for added lines. Luckily, there's no need to look for suitable colors as they are found on github.com.
As you know, Geany can highlight diffs/patch files. The main point of doing this is to make changed lines more visible, outstanding, because they are the important stuff. So yes, highlighting. Dark Fruit Salad and Zenburn are not even trying. But don't take my word for it; take any diff and try them. Both themes do highlighting of added lines poorly, but both fail miserably in case of deleted lines.
I didn't try experimenting with colors yet, but there are themes that I personally feel being particularly good at highlighting diffs, like Tango Light and Kugel (conventional red and green) and Oblivion 2 (unusual green and blue).
You can also say that GitHub theme went wrong with acid green on white for added lines. Luckily, there's no need to look for suitable colors as they are found on github.com.