8237453: [TabPane] Incorrect arrow key traversal through tabs after reordering

[arapte]

Issue:
Dragging a tab and dropping it back to it's original position causes an incorrect reordering of tabs. Incorrect order of tabs can be observed using arrow key traversal through tabs.

Cause:
Below mechanism of identifying if tab header is dragged and dropped at same position is not reliable.
When a tab is selected for dragging, the tab's layout X is stored as dragHeaderStartX.
When the tab is dropped, the tab's destination layout X is saved as dragHeaderDestX.
These two values are used to decide if the reordering of tabs is needed.
This is an unreliable mechanism in two cases,

1. When the TabPane.TabClosingPolicy is set to TabPane.TabClosingPolicy.SELECTED_TAB, the close button icon gets added only to the selected tab.
   Each time when the tab selection is changed, the header region needs a re-layout. When a non selected tab is chosen for dragging dragHeaderStartX and dragHeaderDestX will always differ.

2. Calculation of dragHeaderDestX involves floating point operation. So the computed dragHeaderDestX may sometimes vary by fraction than dragHeaderStartX.

Fix:
Use the index of tab header for identifying the tabs which are reordered.
Save the index when reordering begins. dragTabHeaderStartIndex
Save the index when tab is dropped. dragTabHeaderIndex
If the index are same then reordering of tabs is NOT needed.
If the index are NOT same then the tabs from dragTabHeaderStartIndex to dragTabHeaderIndex are reordered.

Verification:
This fix is specific to TabPane reordering. No other tests/behavior should be affected.
Added a new system test.

Progress

• Change must not contain extraneous whitespace
• Commit message must refer to an issue
• Change must be properly reviewed

Issue

JDK-8237453: [TabPane] Incorrect arrow key traversal through tabs after reordering

Approvers

• Kevin Rushforth (kcr - Reviewer)
• Ajit Ghaisas (aghaisas - Reviewer)

[bridgekeeper]

👋 Welcome back arapte! A progress list of the required criteria for merging this PR into master will be added to the body of your pull request.

[mlbridge]

Webrevs

• 00: Full (835e7aa)

[kevinrushforth]

Looks good.

[openjdk]

@arapte This change now passes all automated pre-integration checks. When the change also fulfills all project specific requirements, type /integrate in a new comment to proceed. After integration, the commit message will be:

8237453: [TabPane] Incorrect arrow key traversal through tabs after reordering

Reviewed-by: kcr, aghaisas

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Since the source branch of this PR was last updated there have been 7 commits pushed to the master branch. Since there are no conflicts, your changes will automatically be rebased on top of these commits when integrating. If you prefer to avoid automatic rebasing, please merge master into your branch, and then specify the current head hash when integrating, like this: /integrate e224e549dd948ef93fda10bf5effcfb255d6c5fe.

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[kevinrushforth]

/reviewers 2

[openjdk]

@kevinrushforth
The number of required reviews for this PR is now set to 2 (with at least 1 of role reviewers).

[kevinrushforth]

I'd like @aghaisas to take a look as well.

[arapte]

/integrate

[openjdk]

@arapte The following commits have been pushed to master since your change was applied:

• e224e54: 8238526: Cherry pick GTK WebKit 2.26.3 changes
• 6968e38: 8237469: Inherited styles don't update when node is moved
• 3c55a7e: Merge
• a4b9f24: 8237503: Update copyright header for files modified in 2020
• 1749e85: 8237975: Non-embedded Animations do not play backwards after being paused
• 2ab40c1: 8231513: JavaFX cause Keystroke Receiving prompt on MacOS 10.15 (Catalina)
• aa91ebb: 8237944: webview native cl "-m32" unknown option for windows 32-bit build

Your commit was automatically rebased without conflicts.

Pushed as commit 21d3b7e.

[mlbridge]

Mailing list message from Ambarish Rapte on openjfx-dev:

Changeset: 21d3b7e
Author: Ambarish Rapte <arapte at openjdk.org>
Date: 2020-02-07 05:59:01 +0000
URL: https://git.openjdk.java.net/jfx/commit/21d3b7e0

8237453: [TabPane] Incorrect arrow key traversal through tabs after reordering

Reviewed-by: kcr, aghaisas

! modules/javafx.controls/src/main/java/javafx/scene/control/skin/TabPaneSkin.java
+ tests/system/src/test/java/test/robot/javafx/scene/TabPaneReorderTest.java