RFR: 6318027: BasicScrollBarUI does not disable timer when enclosing frame is disabled.

[Abhishek Kumar]

On Fri, 26 Jul 2024 06:03:28 GMT, Prasanta Sadhukhan <psadhukhan at openjdk.org> wrote:

> Issue is
> BasicScrollBarUI.ArrowButtonListener starts a timer in mousePressed(), and stops it in mouseReleased(). If the frame containing the scrollbar is disabled between the MOUSE_PRESSED and the MOUSE_RELEASED events, the mouseReleased() method is never called. If the frame is then re-enabled, the still-running timer causes it to scroll all the way to the end.
> Fix is to check if [ArrowButtonListener.handledEvent](https://github.com/openjdk/jdk/blame/ee839b7f0ebe471d3877cddd2c87019ccb8ee5ae/src/java.desktop/share/classes/javax/swing/plaf/basic/BasicScrollBarUI.java#L1567) is still set when ActionEvent is processed then stop the timer and reset this variable.
> 
> CI testing is green and also SwingSet2 JScrollPane scrolling with this modification..

test/jdk/javax/swing/JScrollBar/DisableFrameFromScrollBar.java line 87:

> 85:                     frame.setSize(150, 150);
> 86:                     frame.setLocationRelativeTo(null);
> 87:                     frame.setVisible(true);

Can be pushed to a helper method.

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PR Review Comment: https://git.openjdk.org/jdk/pull/20346#discussion_r1699411655