> just to render Markdown

Rendering text beyond ASCII is famously difficult to do; rendering formatted text is sometimes difficult to even make sense of (e.g. what should a style change in the middle of an Arabic word do? how about a selection boundary being moved with arrow keys?); rendering honest-to-goodness Markdown, which can technically include arbitrary HTML tags, is nowhere in the vicinity of a small project.

None of which is to say that you shouldn’t demand that a toolkit solve it for you, only that I understand why the RichEdit control reportedly had a separate team allocated to it in turn-of-the-millenium Microsoft. Working with a large amount of formatted text feels like it should be the most complicated feature of any UI toolkit and I shudder at the thought of even designing the API for it.

(A web browser is good at all this. It also has the API surface of a web browser.)

And some things will still be on you regardless. Did you know Android has two modes for text wrapping, one that won’t reflow the entire paragraph after a single-word change at the end and a different one whose results embarrass a typographer from half a millenium ago? That’s very much the correct way to do things, but if you’re streaming text in, it’s on you to decide whether you want subpar wrapping throughout or a layout jump whenever a paragraph break arrives. Most importantly, it’s on you to know the question exists; there are more, some more important than this one.

(Modern toolkits aren’t the only ones that can be bad at scaling to large amounts of data, either. Notably, Microsoft had to write an entire new “windowless” one to replace USER’s heavyweight window-based one so that Access wouldn’t collapse under its own weight. They then reused it for IE, for similar reasons. Raymond Chen’s response[1] to complaints about that toolkit staying private to Microsoft amounted to “fuck off”.)

[1] https://devblogs.microsoft.com/oldnewthing/20050211-00/?p=36...