RFR: 6911375: mouseWheel has no effect without vertical scrollbar [v2]

[Alexey Ivanov]

On Mon, 28 Feb 2022 07:59:24 GMT, Prasanta Sadhukhan <psadhukhan at openjdk.org> wrote:

>> It is observed that mouseWheel doesn't scroll through a list if there is no scrollbar even though pressing PageUp/Down using keyboard moves up/down the list.
>> Issue stems from the fact that BasicScrollPaneUI.Handler.mouseWheelMoved() skips the mouse wheel events when the scrollbar is not visible. 
>> Fixed to handle mouseWheelEvent even though scrollbar is not visible with the assumption that if both vertical and horizontal scrollbar is not visible, then assume default orientation to be vertical.
>> 
>> Existing jtreg, jck tests are ok. All L&F works well with the fix and testcase works in all platforms except on mac which will be handled separately.
>
> Prasanta Sadhukhan has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Fix test comments

test/jdk/javax/swing/JScrollPane/TestMouseWheelScroll.java line 48:

> 46:     static Point p;
> 47:     static int width;
> 48:     static int height;

These three should also be volatile, shouldn't they?

test/jdk/javax/swing/JScrollPane/TestMouseWheelScroll.java line 101:

> 99:                 robot.delay(1000);
> 100:                 robot.mouseWheel(1);
> 101:                 robot.delay(500);

You don't call `waitForIdle` or `delay` after the mouse click because it just selects an item but doesn't change the position, right?

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PR: https://git.openjdk.java.net/jdk/pull/7585