Allow slow clicks in the UI

[martenbjork]

Maybe this is an EGUI implementation decision — I'm curious to learn more.

When clicking things in Rerun, the click "times out" after ~750ms.

✅ Working: Mousedown, wait 100ms, mouse up = Click is registered
❌ Not working: Mousedown, wait 1000ms, mouse up = Click is not registered

If you slow-click an interactive element, like the > Blueprints toggle in the selection view, you can see this behavior in action. After ~750ms, the visual click state disappears as if your click has been cancelled.

Is there good rationale for this? I often slow-click, when I suddenly have doubt about whether I want to go through with the click. (Mousedown => Haaaaang on... => drag mouse outside control => release => phew!)

[abey79]

Well spotted!

The phenomenon definitely deserve investigation. That said, I think those header would benefit from registering mouse down instead of up, like #2858.

[emilk]

Yes, this is currently hardcoded in egui:

• https://github.com/emilk/egui/blob/0e5f93b65d7613de58ce8d16e9eba652d1d3d562/crates/egui/src/input_state.rs#L14-L15

The rational is that we need some way to distinguish a click from a drag. If the user clicks and holds an element, egui assumes you are intending to drag it.