<Swing Dev> [13] Review Request: 8226653 [accessibility] Can edit text cell correctly, but Accessibility Tool reads nothing about editor

[Sergey Bylokhov]

Hello.
Please review the fix for JDK 13.

Bug: https://bugs.openjdk.java.net/browse/JDK-8226653
Fix: http://cr.openjdk.java.net/~serb/8226653/webrev.01

Short description:

   If the user starts to edit the cell in the "default" JTable then we
show the text editor in the cell but did not transfer the focus to it.
This feature breaks the accessibility tools, which cannot report
information about the current editor.
I suggest to try it in the SwingSet2 to see how this feature actually
works. The idea of the current fix is to disable this feature + some
other related small fixes.


Long description(from small changes to big):

  - CAccessible.java:
     When the user completes the editing of the cell we post
     ACCESSIBLE_TABLE_MODEL_CHANGED event, and we need to notify the
     native system that the data inside the table was changed.

  - JTable.processKeyBinding():
     1) We do not want to start editing of the cell if the only modifier
        key is pressed, but some of the modifier keys were missed:
        VK_ALT_GRAPH and KeyEvent.VK_META(which is CMD key on the macOS).
     2) To enable the "surrendersFocusOnKeystroke" property, I have to add
        one more flag, because I cannot do this via the public API:
        https://docs.oracle.com/en/java/javase/11/docs/api/java.desktop/javax/swing/JTable.html#setSurrendersFocusOnKeystroke(boolean)
        Note that it is specified as "false" by default, and setting it
        to "true" even under the Accessibility tool may break the spec.
        Probably we need to clarify this behavior in JDK 14.

  - JTable.java.getAccessibleAt()/getAccessibleChild():
     The accessibility API represent the table as a grid of cells, and ignores
     the real child of the table. Each cell is represented as a
     AccessibleJTableCell, this AccessibleJTableCell is used as a proxy object
     and transfer all requests to the real component which is responsible to
     draw the cell. Note that it is specified that the render is returned by
     some of its methods:
     https://docs.oracle.com/en/java/javase/11/docs/api/java.desktop/javax/swing/JTable.AccessibleJTable.AccessibleJTableCell.html#getCurrentAccessibleContext()
     So we cannot modify these methods to return context of the editor, instead
     I added the switch before we return "AccessibleJTableCell".
     In JDK 14 it can be moved to the "right" place.


Addition thoughts about "FocusOnKeystroke" feature:
  - We can leave this feature as-is and report the current editor to
    the accessibility tool even if the editor is not focused, but this may
    confuse the user because it will not be possible to move the cursor or
    select the text from the keyboard and this is not expected behavior of the
    text editor.
  - We also can disable the editing of the cell on the fly, and start it only
    if the user emulates the mouse click inside the table.
  - Or we can leave everything as-is and move the responsibility for this
    feature to the application, which will enable or disable "FocusOnKeystroke" feature.

-- 
Best regards, Sergey.