Mnemonic Parsing doesn't appear to work properly

[John Hendrikx]

Hm, I can confirm it appears under the "e", also under Windows, but I 
suspect the platform will make no difference.

I tested a bit further, and I found the following:

1) The mnemonic key seems to be "m", and it appears under the "e" 
because it deleted two more underscores (index is off by 2). What makes 
this hard to discover however is my second finding:

2) Checkbox doesn't toggle at all when you use the correct mnemonic, a 
Button however works.

3) If you add an "onAction" to the Checkbox that prints something on the 
console, you can see the mnemonic working, but the Checkbox is still not 
toggled.

I checked the mnemonic parsing code, and if you run it in isolation, it 
finds the first underscore and has the correct index 
(TextBinding#parseAndSplit). I stopped there, but perhaps the code 
actually runs for each underscore found (it updates the text, perhaps 
this triggers another parsing run).

--John

On 29/10/2021 19:53, Scott Palmer wrote:
> I looked in the bug database and while there are lots of bugs reported
> against the mnemonic parsing, they claim to be fixed.
>
> After noticing something peculiar on a control in my app (it was showing a
> file path and I hadn't disabled the mnemonic parsing) I did some tests.
>
> The documentation is unclear on what should happen if multiple underscores
> are in the text.  It just says if the mnemonic parsing character '_'
> appears that the key combination will be based on the succeeding
> character.  I presume that it should pick only ONE of the underscores and
> subsequent character, either the first or the last would make sense.
> However, the behavior is that an unrelated character is shown as the
> mnemonic and even it doesn't actually do anything.  Tested with JDK 17.0.1
> and JavaFX 17.0.1.
>
> Does this behave as expected for you?
>
>
> package mnemonic_parsing_bug;
>
> import javafx.application.Application;
> import javafx.geometry.Insets;
> import javafx.scene.Scene;
> import javafx.scene.control.CheckBox;
> import javafx.scene.control.Label;
> import javafx.scene.layout.VBox;
> import javafx.stage.Stage;
>
> public class Main extends Application {
>
>     public static void main(String[] args) {
>         launch(args);
>     }
>
>     @Override
>     public void start(Stage primaryStage) throws Exception {
>         Label titleLabel = new Label("""
>             The CheckBox below has text set to 'How_to_Test_Mnemonics'.
>             On Windows press the Alt key to see where the underlined
> character appears.
>             It shows under the 'e' in Mnemonics for me, and I can't figure
> out
>             what key combination (if any) actually does something.
>             [JavaFX Version %s]""".formatted(System.getProperty(
> "javafx.version")) );
>         titleLabel.setMnemonicParsing(false);
>         CheckBox mnemonicCB = new CheckBox("How_to_Test_Mnemonics");
>         mnemonicCB.setMnemonicParsing(true);
>         VBox box = new VBox(8,titleLabel, mnemonicCB);
>         box.setPadding(new Insets(16));
>         Scene scene = new Scene(box);
>         primaryStage.setTitle("Mnemonic Parsing Bug");
>         primaryStage.setScene(scene);
>         primaryStage.show();
>     }
>
> }
>