While you can change resizing behavior of a stage using Stage.setResizable() you cannot do that using Stage.resizableProperty().set(). Probably related problem is that binding to resizableProperty has no effect.

Here is a sample program that illustrates that is below. You can resize a window only when "resizable" check box is set, not when only "resizableProperty" is set:
{code}
import javafx.application.Application;
import javafx.beans.value.ChangeListener;
import javafx.beans.value.ObservableValue;
import javafx.scene.GroupBuilder;
import javafx.scene.Scene;
import javafx.scene.SceneBuilder;
import javafx.scene.control.CheckBox;
import javafx.scene.control.CheckBoxBuilder;
import javafx.scene.layout.VBoxBuilder;

/**
 * Test resizing behaviour of a stage using Stage.setResizable() and Stage.resizableProperty().set().
 */
public final class ResizablePropertyBug extends Application {


    public static void main(String[] args) {
        Application.launch(args);
    }

    @Override
    public void start(final Stage stage) {
        final CheckBox checkBoxResizable = CheckBoxBuilder.create()
                .text("resizable")
                .build();
        final CheckBox checkBoxResizableProperty = CheckBoxBuilder.create()
                .text("resizableProperty")
                .build();
        final Scene scene = SceneBuilder.create()
                .width(270)
                .height(370)
                .root(GroupBuilder.create()
                        .children(
                                VBoxBuilder.create()
                                        .layoutX(30)
                                        .layoutY(20)
                                        .spacing(10)
                                        .children(
                                                checkBoxResizable,
                                                checkBoxResizableProperty
                                        )
                                        .build()
                        )
                        .build()
                )
                .build();

        stage.setResizable(checkBoxResizable.selectedProperty().getValue());
        stage.resizableProperty().set(checkBoxResizableProperty.selectedProperty().getValue());

// checkBoxResizableProperty.selectedProperty().bindBidirectional(stage.resizableProperty());
        checkBoxResizable.selectedProperty().addListener(new ChangeListener<Boolean>() {
            @Override
            public void changed(ObservableValue<? extends Boolean> ov, Boolean t, Boolean t1) {
                stage.setResizable(checkBoxResizable.selectedProperty().getValue());
            }
        });
        checkBoxResizableProperty.selectedProperty().addListener(new ChangeListener<Boolean>() {
            @Override
            public void changed(ObservableValue<? extends Boolean> ov, Boolean t, Boolean t1) {
                stage.resizableProperty().set(checkBoxResizableProperty.selectedProperty().getValue());
            }
        });

        stage.setScene(scene);
        stage.setTitle("Stage resizableProperty test");
        stage.show();
    }
}
{code}