RFR: 8261840: Submenus close to screen borders are no longer repositioned

[Kevin Rushforth]

On Fri, 12 Mar 2021 10:03:53 GMT, Ajit Ghaisas <aghaisas at openjdk.org> wrote:

>> Reverting to the old way of showing the context menu but with application
>> of CSS prior to calling prefHeight(-1) / prefWidth(-1) to ensure correct
>> size measurement of the menu.
>
> Marked as reviewed by aghaisas (Reviewer).

This fixes the bug in question, although I see a slight regression in behavior on Windows with 125% pixel scaling (it doesn't reproduce with any other scaling value that I tried). With the original test case for [JDK-8228363](https://bugs.openjdk.java.net/browse/JDK-8228363), and `TOP` as the value of `side`, the initial menu is positioned slightly lower (by a few pixels) than it should be. See the attached image. It is correct the second and subsequent times the context menu is opened.

Given that this new bug only happens with 125% scaling, it seems likely that it is a preexisting bug, and this fix merely exposes it. Can you take a look at this? If it is preexisting, then we should file a follow-on bug for this.

![ContextMenu-125](https://user-images.githubusercontent.com/34689748/110947924-9991ce00-82f5-11eb-82d2-6959ef24293f.png)

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PR: https://git.openjdk.java.net/jfx/pull/410