RFR: 8237491: Undecorated stage cannot be maximized [v2]

[Thiago Milczarek Sayao]

> Simple fix to enable maximizing functionality on the window manager.
> 
> Test provided
>  gradlew -PFULL_TEST=true -PUSE_ROBOT=true :systemTests:test --tests test.javafx.stage.MaximizeUndecorated
> 
> Fix for linux only.

Thiago Milczarek Sayao has updated the pull request incrementally with one additional commit since the last revision:

  Requested adjustments

-------------

Changes:
  - all: https://git.openjdk.java.net/jfx/pull/345/files
  - new: https://git.openjdk.java.net/jfx/pull/345/files/821e9ad2..586723e9

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=jfx&pr=345&range=01
 - incr: https://webrevs.openjdk.java.net/?repo=jfx&pr=345&range=00-01

  Stats: 8 lines in 2 files changed: 5 ins; 1 del; 2 mod
  Patch: https://git.openjdk.java.net/jfx/pull/345.diff
  Fetch: git fetch https://git.openjdk.java.net/jfx pull/345/head:pull/345

PR: https://git.openjdk.java.net/jfx/pull/345