RFR: 8155030: The Menu Mnemonics are always displayed for GTK LAF [v8]

[Alexey Ivanov]

On Mon, 24 Jun 2024 07:21:49 GMT, Abhishek Kumar <abhiscxk at openjdk.org> wrote:

>>>Requesting the value of RootPane.altPress from UIManager each time postProcessKeyEvent is called is inefficient, so you can store the value in altProcessor when look and feel is installed.
>> 
>> I guess you are pointing out the code in SynthGraphicsUtils.paintText method where RootPane.altPress value is retrieved from UIManager each time. Storing the value in it's constructor doesn't reflect the correct value and is always `false`.
>
>> If RootPane.altPress can be changed dynamically, you can install a PropertyChangeListener to UIManager.
> 
> I think it can be changed but is it really required to handle it ?
> I mean why does a user change it dynamically ?

> In my initial fix, I added the `altProcessor` handler in `SynthLookAndFeel.initialize` with condition check for GTK L&F. Phil has suggested not to check for GTK L&F instead look for some alternate way like mentioned [here](https://github.com/openjdk/jdk/pull/18992#discussion_r1595782003).
> 
> So, the handler implementation is moved to `SynthRootPaneUI`.

Thus, out of Synth-derived Look and Feels, only GTK needs the feature. Can't the listener be installed in `GTKLookAndFeel.initialize`?

At the same time, if you install the listener in `SynthLookAndFeel`, other L&F based on Synth could also use this feature, thus your way is more flexible.

However, `SynthRootPaneUI` is still part of the base class… I still don't understand how it's different from what I'm proposing.

I'd like to avoid keeping a flag whether the listener is installed or not… But there could be no other way since not all Synth-based L&Fs enable hiding mnemonics.

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PR Review Comment: https://git.openjdk.org/jdk/pull/18992#discussion_r1652996654