[webkit-changes] [WebKit/WebKit] 410bb5: REGRESSION: Horizontal scroll-to-end is very slow ...

[Richard Robinson]

  Branch: refs/heads/main
  Home:   https://github.com/WebKit/WebKit
  Commit: 410bb5f43c2e76507d7ab0716bb5664b9b420c4d
      https://github.com/WebKit/WebKit/commit/410bb5f43c2e76507d7ab0716bb5664b9b420c4d
  Author: Richard Robinson <richard_robinson2 at apple.com>
  Date:   2023-01-09 (Mon, 09 Jan 2023)

  Changed paths:
    M Source/WebCore/platform/KeyboardScrollingAnimator.cpp

  Log Message:
  -----------
  REGRESSION: Horizontal scroll-to-end is very slow (and maybe shouldn't happen at all?)
https://bugs.webkit.org/show_bug.cgi?id=250251
rdar://103969202

Reviewed by Simon Fraser.

This bug was happening because when modifier keys are applied to a key press,
AppKit sends a `keyDown` event to the UIProcess, but does not send a corresponding
`keyUp` event. This causes scrolling to never stop.

This PR changes this behavior so that no scrolling will happen with `Cmd+Left/Right arrow`,
`Shift+Left/Right arrow`, or `Cmd+Shift+Left/Right arrow`. This behavior is
better because these were never technically valid key combos in the first place,
and simply pressing the left or right arrow accomplishes the desired scrolling.
`Cmd+Left/Right arrow` also sometimes interferes with page back/forward keyboard
shortcuts, so this will avoid that as well.

* Source/WebCore/platform/KeyboardScrollingAnimator.cpp:
(WebCore::scrollGranularityForKeyboardEvent):

Canonical link: https://commits.webkit.org/258686@main