The attached NetBeans project load an FXML that defines a Rectangle this way:

<AnchorPane id="AnchorPane" maxHeight="-Infinity" maxWidth="-Infinity" minHeight="-Infinity" minWidth="-Infinity" prefHeight="400.0" prefWidth="600.0" xmlns:fx="http://javafx.com/fxml">
  <children>
    <Rectangle arcHeight="5.0" arcWidth="5.0" fill="DODGERBLUE" height="200.0" layoutX="200.0" layoutY="100.0" stroke="BLACK" strokeType="INSIDE" style="-fx-stroke-width: 10;&#10;-fx-stroke-type: inside;" width="200.0" />
  </children>
</AnchorPane>

Run options contains -Duser.language=tr -Duser.country=TR so that default locale is Turkish.
You get the stack below.
Simply change "-fx-stroke-width: inside;" to "-fx-stroke-width: centered;" to get rid of the stack.

WARNING: com.sun.javafx.css.StyleHelper calculateValue caught:
java.lang.IllegalArgumentException: No enum constant javafx.scene.shape.StrokeType.inside
at java.lang.Enum.valueOf(Enum.java:236)
at com.sun.javafx.css.converters.EnumConverter.convert(EnumConverter.java:60)
at com.sun.javafx.css.converters.EnumConverter.convert(EnumConverter.java:37)
at com.sun.javafx.css.ParsedValue.convert(ParsedValue.java:265)
at com.sun.javafx.css.StyleHelper.calculateValue(StyleHelper.java:1535)
at com.sun.javafx.css.StyleHelper.lookup(StyleHelper.java:1139)
at com.sun.javafx.css.StyleHelper.transitionToState(StyleHelper.java:861)
at javafx.scene.Node.impl_processCSS(Node.java:7419)
at javafx.scene.Parent.impl_processCSS(Parent.java:1153)
at javafx.scene.Node.processCSS(Node.java:7387)
at javafx.scene.Scene.doCSSPass(Scene.java:443)
at javafx.scene.Scene.preferredSize(Scene.java:1445)
at javafx.scene.Scene.impl_preferredSize(Scene.java:1512)
at javafx.stage.Window$10.invalidated(Window.java:719)
at javafx.beans.property.BooleanPropertyBase.markInvalid(BooleanPropertyBase.java:127)
at javafx.beans.property.BooleanPropertyBase.set(BooleanPropertyBase.java:161)
at javafx.stage.Window.setShowing(Window.java:782)
at javafx.stage.Window.show(Window.java:797)
at javafx.stage.Stage.show(Stage.java:229)
at glop.GlopTest.start(GlopTest.java:37)
at com.sun.javafx.application.LauncherImpl$5.run(LauncherImpl.java:319)
at com.sun.javafx.application.PlatformImpl$5.run(PlatformImpl.java:207)
at com.sun.javafx.application.PlatformImpl$4.run(PlatformImpl.java:173)
at com.sun.glass.ui.InvokeLaterDispatcher$Future.run(InvokeLaterDispatcher.java:76)