RFR: 8316423: [linux] Secondary Stage does not respect Scene's dimensions when shown [v2]

[Thiago Milczarek Sayao]

> It looks like a condition between calls from `set_visible` to `request_focus`. When `request_focus` is called, the window is not yet mapped (map is requested on `set_visible`). 
> 
> 200x200 is the default gtk window size if none is specified. Since the window is presented at the requested size and then changes to 200x200 I would guess the size request on `gtk_window_present` (which is called on `request_focus`) is being queued and released later. But I'm not really sure.
> 
> With this change immediate `request_focus` after the window is created will be ignored. But the default is to request focus on map, so it will work. `request_focus` will only be useful when called after the window is mapped (presented on the screen).
> 
> This also fixes [JDK-8316425](https://bugs.openjdk.org/browse/JDK-8316425)

Thiago Milczarek Sayao has updated the pull request incrementally with two additional commits since the last revision:

 - Re-enable tests
 - Fix fullscreen position

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

Changes:
  - all: https://git.openjdk.org/jfx/pull/1249/files
  - new: https://git.openjdk.org/jfx/pull/1249/files/7b9001dd..c5b631d5

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jfx&pr=1249&range=01
 - incr: https://webrevs.openjdk.org/?repo=jfx&pr=1249&range=00-01

  Stats: 22 lines in 2 files changed: 0 ins; 21 del; 1 mod
  Patch: https://git.openjdk.org/jfx/pull/1249.diff
  Fetch: git fetch https://git.openjdk.org/jfx.git pull/1249/head:pull/1249

PR: https://git.openjdk.org/jfx/pull/1249