RFR: 6415065: Submenu is shown on wrong screen in multiple monitor environment

[Sergei Tachenov]

On Thu, 10 Aug 2023 00:04:52 GMT, Sergey Bylokhov <serb at openjdk.org> wrote:

>> Hello!
>> 
>> I'm a member of the UI team in JetBrains IntelliJ department, and we have this bug with popup menus being shown on the wrong monitor in multi-monitor environments:
>> 
>> https://youtrack.jetbrains.com/issue/JBR-5824/Dual-monitor-bug-on-the-context-menu
>> 
>> I managed to track it down to this JDK bug:
>> 
>> https://bugs.openjdk.org/browse/JDK-6415065
>> 
>> I've described the cause and the fix in the commit message, but in short, what happens here is that `JMenu.getPopupMenuOrigin` sometimes returns coordinates outside (usually above) of the current screen, and later `JPopupMenu.adjustPopupLocationToFitScreen` uses those coordinates to fit the entire popup menu into the screen, which goes wrong because at that point it's no longer known which screen the menu was initially invoked on.
>> 
>> I've fixed this by making sure the Y coordinate is still within the correct screen when it's returned from `JMenu.getPopupMenuOrigin`.
>
> src/java.desktop/share/classes/javax/swing/JMenu.java line 489:
> 
>> 487:         }
>> 488:         if (position.y + y >= screenBounds.y + screenBounds.height) { // Below the current screen?
>> 489:             y = screenBounds.y + screenBounds.height - 1 - position.y; // Fit into the screen, relative to our origin.
> 
> why only the y coordinate is checked? Can we implement it for x as well for symmetry?

A good idea. I was actually thinking about it after I had submitted this. Even though I've never encountered any issues with the X coordinate, I think it's still possible in theory in some unusual circumstances. Anyway, an extra check definitely won't hurt. Will do.

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PR Review Comment: https://git.openjdk.org/jdk/pull/15185#discussion_r1289553429