20 years ago I worked on some Java applications as a college student curious to compare AWT/Swing to other options, and I found that the cross-platform renderin

20 years ago I worked on some Java applications as a college student curious to compare AWT/Swing to other options, and I found that the cross-platform rendering worked decently well, but that the underlying architecture and algorithms were hot garbage. For instance, if you had a full-screen panel nested in a full screen panel, and you put the CPU under heavy load, you could watch it fill both background colors despite the front panel completely obscuring the back panel. Using Windows native API "windows" the paint events would only happen for the un-obscured components and only for the regions exposed. Java advocates advertised how "lightweight" their components were because they "didn't depend on a heavy-weight operating system window object" when in fact those "heavyweight" window objects were part of an algorithm that performed much better. Another big annoyance was that every UI event was delivered in its own thread, so you had to deal with all the complexities of multithreading just trying to write simple user interfaces. I had a whole blog-sized article I wrote once about all the design deficiencies; I've forgotten most of the rest of those details. Java actually succeeded quite well at being cross-platform, it just wasn't a design worth being cross-platform in the first place. Hopefully they fixed some of this in 20 years.