I have a frame which contains scrollpane having ScrollPane.SCROLLBARS_AS_NEEDED policy set to it. A button is added to the scrollpane. While resizing the frame (make the frame to be smaller) scrollbars of the scrollpane can be seen , but just for a second ( flashes ).

import java.awt.ScrollPane;
import java.awt.Frame;
import java.awt.Button;

public class TestScrollPaneResize {
        private Frame frame=null;
        private ScrollPane sp=null;
        private Button b=null;

        TestScrollPaneResize(){
                frame = new Frame("Test ScrollPane resize test");
                sp = new ScrollPane( ScrollPane.SCROLLBARS_AS_NEEDED );
                sp.add(new Button("Press Me..!"));
                frame.add("Center",sp);
                frame.setSize(300,300);
                frame.setVisible(true);
        }
        public static void main(String []args){
                new TestScrollPaneResize();
        }
}

Step to Reproduce:
-------------------
1) Run the attached program.
2) Resize the frame(to make it smaller). Move the mouse to the left bottom corner of the frame, Press the mouse left button & move towards inside. Observe carefully, while releasing the mouse ,you can see the scrollbars just for a second(flashes). If you see the same then the bug is reproduced.
This happens only in XToolkit(i used mustang b101), this can't be seen in Motif toolkit ( i used 1.5.0/fcs/b64). Hence this is a regression.