input (wasm): buggy behaviour when losing focus during key press

[eliasdaler]

Repro (I tested on Ubuntu 20.04 and Firefox and Chromium):

1. Go to Keyboard example
2. Hold any key
3. While holding the key, click to another tab / window
4. Release the key
5. Go back to the example - you'll see that Ebiten thinks that the key is still pressed - the only way to "reset" it is to press the key again

This probably happens because Ebiten doesn't catch "key released" event when out of focus.

I think that Ebiten should poll all input on focus gain if it's possible (that's the only way for it to determine the current state of the keyboard if it lost some events).

[hajimehoshi]

Thanks! I don't think it is possible to poll such key inputs on browsers, but do you have any suggestions about implementation?

[eliasdaler]

Ebiten stores the whole input state somewhere, right?
I think that it can "reset" every "key pressed" to false on focus gain, and set everything as if nothing is currently being pressed, unless it gets a new "key press" event.

[hajimehoshi]

I'm not sure this is so obvious, but let me investigate... Thanks!