When comparing Seesaw vs FLTK, the Slant community recommends FLTK for most people. In the question“What are the best cross-platform GUI toolkits?” FLTK is ranked 12th while Seesaw is ranked 37th. The most important reason people chose FLTK is:
It's simple design and lack of more advanced C++ features makes it easy for beginners.
Specs
Ranked in these QuestionsQuestion Ranking
Pros
Pro Built on top of Swing
Swing has some negative aspects about it - it's complex and difficult. However, it's stable and can stand alone. Seesaw essentially fills in the gaps that Swing leaves. It patches a lot of the workarounds and hacks that are required with Swing, and allows you to use all the benefits of Swing with considerably less code.
Pro Simplicity
It's simple design and lack of more advanced C++ features makes it easy for beginners.
Pro Fast
Well-designed widgets, coded with careful attention to rendering/execution speed.
Pro Stable
FLTK code developed more than 10 years ago still compiles and runs perfectly, without changes.
Pro Lightweight
Uses a limited and lightweight design and restricts itself to solely GUI functionality. Because of this restriction, the FLTK hello world example is only about 100 KiB.
Pro GUI designer
Fast Light User-Interface Designer (FLUID) included.
Cons
Con Can be too simple for some projects
FLTK offers far fewer widgets than most other toolkits.
Con Does not look like a native application
Because it uses non-native widgets, it doesn't look like a native application on any platform.