Take the Code Example demo initially opened: drag age up to 120, then press the Increment button, and watch the label “Arthur is 120” briefly blip to “Arthur is 121” (while the DragValue still shows 120!) before being dragged back down to 120 presumably by rerendering and egui::DragValue::new(age).range(0..=120) clamping it.

That’s… eww. It probably doesn’t often cause real problems—though it surely could, as it’s allowing temporary rendering with out-of-bounds values that a developer might have expected to be clamped—but it’s still very eww, the idea that mutating data leads to parts of a frame being rendered with different data.