FULL PRODUCT VERSION :
java version "1.8.0_51"
Java(TM) SE Runtime Environment (build 1.8.0_51-b16)
Java HotSpot(TM) 64-Bit Server VM (build 25.51-b03, mixed mode)


ADDITIONAL OS VERSION INFORMATION :
Linux xxxx 3.13.0-61-generic #100-Ubuntu SMP Wed Jul 29 11:21:34 UTC 2015 x86_64 x86_64 x86_64 GNU/Linux


EXTRA RELEVANT SYSTEM CONFIGURATION :
Ubuntu 14.04 LTS, x64 desktop.

A DESCRIPTION OF THE PROBLEM :
Setting stage.setResizable(false); will only remove the "minimize" and "maximize" window decorators (which is expected).

It will not prevent the window from being resized using the mouse, via dragging the edge/corner.

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
Then, using the mouse by clicking on the border of the window, you can resize the stage.

EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
I would expect the same behavior as Windows/Mac, where the stage is not resizable.
ACTUAL -
The stage can be resized using the mouse, and it shouldn't be.

ERROR MESSAGES/STACK TRACES THAT OCCUR :
Stacktrace indicates that the (native) GTK windowing sub-system is still registered for window resize events.

REPRODUCIBILITY :
This bug can be reproduced always.

---------- BEGIN SOURCE ----------
      class stageTest {
            public
            stageTest() {
                final Stage stage = new Stage(StageStyle.UTILITY);
                stage.setTitle("RESIZE TEST");
                stage.setWidth(300);
                stage.setHeight(140);
                stage.setResizable(false);

                stage.showAndWait();
            }
        }

        final stageTest stageTest = new stageTest();
---------- END SOURCE ----------