RFR: 8251240: Menus inaccessible on Linux with i3 wm

[Jose Pereda]

On Sun, 9 Jul 2023 17:43:05 GMT, Thiago Milczarek Sayao <tsayao at openjdk.org> wrote:

> The bug happens because `gdk_window_get_frame_extents` is not returning the correct position when o i3-wm, probably by some bug on the wm itself.
> 
> Te fix replaces the usage of the function for already known extents value calculation.

Looks good to me!
Tested on Ubuntu and Ubuntu with i3 window manager. 
Passes on the latter after this patch, and fails before it.

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Marked as reviewed by jpereda (Reviewer).

PR Review: https://git.openjdk.org/jfx/pull/1173#pullrequestreview-1520952236