RFR: 8360886: Cmd + plus shortcut does not work reliably

[Martin Fox]

On Mon, 30 Jun 2025 16:58:00 GMT, Martin Fox <mfox at openjdk.org> wrote:

> The Mac platform code figures out where characters are on the keyboard as the user types. The character table is updated on every key press by calling a registerKeyEvent: in GlassApplication. This character table is used to resolve KeyCharacterCombination accelerators like Cmd + "+".
> 
> On a US English layout when the user types Cmd + "+" on the main keyboard they're actually typing Cmd + "=". There's special handling in macOS for this combination that can cause two NSEvents to be sent and so there's special handling in the Glass code so we don't process both events. When this special case is invoked registerKeyEvent: isn't being called to update the character table. This bug was introduced when code was consolidated in PR #1528.
> 
> The fix is a simple one-liner. I've added a test for this in the KeyboardTest.java program. It's an isolated test because it requires the Robot to send events to hold down a modifier while a character key is pressed. I also updated some obsolete comments and tweaked it to test all KeyCharacterCombinations since they should now work reliably on all platforms.

Well, now I’ve gone and re-written this PR.

As stated earlier sometimes a single key press can lead to multiple calls to performKeyEquivalent. During testing I discovered that the way Glass checks for this doesn’t always work. Currently it tries to guess which key event might lead to a second one but there are cases where it guesses wrong (e.g. the Hebrew layout). I’ve decided to take a different approach, detecting and discarding the second event. The logic is:

- Is the new key event not the current event (theEvent != NSApp.currentEvent)?
- Are we still working on an earlier event (NSApp.currentEvent == lastKeyEvent)?

If both these conditions are true we can ignore the new key event.

I’ve reverted the changes to the manual test and added a system test. It covers a smattering of carefully selected keys including the combinations involved in this bug. Currently it’s restricted to macOS and Latin keyboards because the Hebrew keyboard on macOS is crazy. I will expand this to other platforms when I have time to do the testing. I’ve run this test on macOS using US English, French, German, Spanish, Hebrew, Devanagari, and a few other layouts.

(About that Hebrew layout. When you hold down Command all the keys start behaving like a US English layout, including the punctuation keys. So the key you press to type a period is entirely different from the key that generates Cmd+period.)

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PR Comment: https://git.openjdk.org/jfx/pull/1837#issuecomment-3045927258