RFR: 8237491: Undecorated stage cannot be maximized

[Kevin Rushforth]

On Mon, 2 Nov 2020 01:08:39 GMT, Thiago Milczarek Sayao <tsayao at openjdk.org> wrote:

> 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.

The fix looks good. I added a couple comments with suggestions and pointed out one thing that must be fixed (the test needs to be excluded on macOS until [JDK-8255835](https://bugs.openjdk.java.net/browse/JDK-8255835) is fixed).

modules/javafx.graphics/src/main/native-glass/gtk/glass_window.cpp line 1347:

> 1345:     is_maximized = maximize;
> 1346:     if (maximize) {
> 1347:         // enable the functionality

Maybe expand this comment similar to what was done for minimize (since the reason for doing it is the same)?

tests/system/src/test/java/test/javafx/stage/MaximizeUndecorated.java line 49:

> 47:     static Stage stage;
> 48:     // might be offscreen and that's ok
> 49:     static final int POS = 1000;

I might recommend something a little smaller (maybe 500 instead of 1000), since some window systems constrain at least the top left corner to be visible.

tests/system/src/test/java/test/javafx/stage/MaximizeUndecorated.java line 80:

> 78: 
> 79:     @Test
> 80:     public void testMaximize() throws Exception {

This test fails on macOS, so you will need to exclude it using `assumeTrue` like this:

    assumeTrue(!PlatformUtil.isMac()); // JDK-8255835

tests/system/src/test/java/test/javafx/stage/MaximizeUndecorated.java line 83:

> 81:         Util.sleep(200);
> 82: 
> 83:         boolean movedToTopCorner = stage.getY() != POS && stage.getX() != POS;

This presumes that the window system will not reposition it (else you will get a false negative). Given that this is using an undecorated window, it should be fine, and I verified that it did correctly detect the failure when your fix is not applied on both Oracle Linux 7.7 and Ubuntu 20.04.

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