RFR: 8280994: [XWayland] Drag and Drop does not work in java -> wayland app direction [v2]

[Phil Race]

On Thu, 1 Jun 2023 18:38:29 GMT, Alexander Zvegintsev <azvegint at openjdk.org> wrote:

>> This change resolves the issue that drag and drop from a Java application to a native Wayland application (such as gedit) is not possible on Linux.
>> 
>> Our code it quite picky for the drop target, and requires it to be a top level window with the WM_STATE property set, whereas the XWayland server provides dummy windows without this property.
>> So now we make an exclusion for this case.
>> 
>> After the fix it successfully passes previously failed related manual jtreg/conformance tests on Wayland.
>> Other tests are also passed.
>
> Alexander Zvegintsev has updated the pull request incrementally with one additional commit since the last revision:
> 
>   fix toolkit if condition

Marked as reviewed by prr (Reviewer).

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PR Review: https://git.openjdk.org/jdk/pull/14266#pullrequestreview-1456088580