My weird example is KDE's Okteta[0]. There are a lot of hex editors (and even more integrated debuggers) but Okteta stands out by being both fully-realized in terms of features and really well-made by the standards of other Qt apps. There are native builds for Mac and Windows[1], and it still sees active development these days. It's one of those dev tools that you get really excited to use, even if it's like bringing a chainsaw to a knife fight. It doesn't do everything, but it's always felt super intuitive to establish offsets, change bytes-per-line or make any other technical adjustment. There are probably more capable hex editors out there, but Okteta's got a good balance of usability and depth. Not sure if that boils down to a lack of contributions or narrow ambitions, but it makes it all the more poignent.
- The Node editor. It does the work of many older interfaces.
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Not complex, but clever and useful:
Corel Draw (at least in the older versions)
- Having pages (instead of artboards), you can easily duplicate a page, and PageUp/PageDown see the evolution of the design. Likewise, for comparing the last changes.
- Ctrl + click a color in the palette, tints a bit the object color. Nice for making colors play well together.
- Double-click a curve and adds a node (without having to select another tool)
[0] https://apps.kde.org/okteta/
[1] https://binary-factory.kde.org/search/?q=okteta