When comparing Seesaw vs Tk, the Slant community recommends Tk for most people. In the question“What are the best cross-platform GUI toolkits?” Tk is ranked 9th while Seesaw is ranked 37th. The most important reason people chose Tk is:
Once you understand how to style, the styling can look great.
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 Easy styling
Once you understand how to style, the styling can look great.
Pro Great for beginners
Easy to pick up and run with it.
Pro Easy and good looking in Mac, Linux and Windows
Pro Bindings for several languages
Bindings for Python, C, C++, Ruby, Perl, Go, Java, Haskell and more, see Languages with a Tk binding.
Cons
Con Base looks are garbage without a good amount of styling
Going with the base look for your app is a bad idea because it looks like garbage with the defaults.
Con C# support lacking
Although the Eagle Project exists, which offers Mono and .NET Core support, C# support is not standard.