EmulationStation bug: L+R at same time

[sleve_mcdichael]

If you enter a system view and scroll more than 1 page away from the top or bottom of the gamelist, then press L and R (PgUp + PgDn) at the same time, then the gamelist will jump a page (up or down, seems random which one) but the cursor will remain in place (now off-screen) with the same initial game highlighted. The gamelist then stays fixed in place while the cursor moves back towards on-screen. (I didn't capture it in my screen-grabs but if you move the cursor away from on-screen, then list scrolls underneath it instead, the other direction, so the cursor does not move any "farther" from the screen.)

Tested and present in both carbon theme and snes-mini theme.

3MB GIF: https://imgur.com/a/NyGZ5Yg

(Edit: this is in emulationstation-dev bb6d8e9, built from source.)

[Lolonois]

@sleve_mcdichael having had a cursory look I can confirm and I lean towards "won't fix".

Rationale: As long as there are SDL events they get pumped into the Window.cpp/GuiComponent::input() call chain an consumed from there. Every downwards component "sees" one event at a time. Processing of the event is stopped either at the last GuiComponent in the chain or if a input() call returns true.

This also happens with Use LR/LB for full page navigation set to false. It just does not occur as easily as the cursor most of the time is always placed middle.

One option to remediate may be to measure the time between the events and if they are too close (i.e. less time than between update()/render() calls) drop the second, and ofc only if the events are LR/LB.