How to delay layout during DND?

Question

I'm writing a feature that allows the user to create controls by dragging and dropping, similar to Keynote.

The simplified code is as follows :

Display display = Display.getDefault() ;
Shell shell = new Shell( display ) ;
shell.setSize( 500, 500 ) ;
shell.setLayout( new FillLayout() ) ;
Composite container = new Composite( shell, SWT.NONE ) ;
GridLayoutFactory.swtDefaults().numColumns(2).applyTo( container ) ;

Composite infoComp = new Composite( container, SWT.NONE ) ;
GridLayoutFactory.swtDefaults().applyTo( infoComp ) ;

Label info = new Label( infoComp, SWT.BORDER ) ;
info.setText( "Create a Button" ) ;
DragSource dragSource = new DragSource( info, DND.DROP_MOVE ) ;
dragSource.setTransfer( new Transfer[] { TextTransfer.getInstance() } ) ;
dragSource.addListener( DND.DragSetData, e -> {
    e.data = "Button" ;
} ) ;

info = new Label( infoComp, SWT.BORDER ) ;
info.setText( "Create a Label" ) ;
dragSource = new DragSource( info, DND.DROP_MOVE ) ;
dragSource.setTransfer( new Transfer[] { TextTransfer.getInstance() } ) ;
dragSource.addListener( DND.DragSetData, e -> {
    e.data = "Label" ;
} ) ;

Composite comp = new Composite( container, SWT.BORDER ) ;
GridDataFactory.swtDefaults().grab(true, true).align(SWT.FILL, SWT.FILL).applyTo(comp);
GridLayoutFactory.swtDefaults().applyTo( comp ) ;

DropTarget dropTarget = new DropTarget( comp,  DND.DROP_MOVE ) ;
dropTarget.setTransfer( new Transfer[] { TextTransfer.getInstance() } ) ;
dropTarget.addListener( DND.Drop, e -> {
    String data = (String) e.data ;
    switch (data) {
        case "Button" -> {
            Button button = new Button( comp, SWT.NONE ) ;
            button.setText( "Button" ) ;
            button.requestLayout() ;
        }
        case "Label" -> {
            Label label = new Label( comp, SWT.NONE ) ;
            label.setText( "Label" ) ;
            label.requestLayout() ;
        }
    }
} ) ;

shell.open() ;
while ( !shell.isDisposed() ) {
    if ( !display.readAndDispatch() ) {
        display.sleep() ;
    }
}
display.dispose() ;

Due to the special treatment of DragSource.drag(Event)

private void drag(Event dragEvent) {
    ...

    String externalLoopKey = "org.eclipse.swt.internal.win32.externalEventLoop";
    int result = COM.DRAGDROP_S_CANCEL;
    try {
        createCOMInterfaces();
        display.setData(externalLoopKey, Boolean.TRUE);
        result = COM.DoDragDrop(iDataObject.getAddress(), iDropSource.getAddress(), operations, pdwEffect);
    } finally {
        display.setData(externalLoopKey, Boolean.FALSE);

        ...
}

org.eclipse.swt.widgets.Composite.layout(Control[], int)

public void layout (Control [] changed, int flags) {
    ...
        /**
         * display.externalEventLoop is true here
         */
        if (!display.externalEventLoop && (flags & SWT.DEFER) != 0) {
            setLayoutDeferred (true);
            display.addLayoutDeferred (this);
        }
        for (int i=updateCount-1; i>=0; i--) {
            update [i].updateLayout (false);
        }
    ...
}

Each Control.requestLayout() call in the handling of the DND.Drop event causes an update to the layout immediately.

In the actual code, the creation process is far more complex than in the example, and need to update the settings area like the one on the right side in Keynote, so requires multiple calls to Control.requestLayout(), there is a lot of overhead.

Is there any way to delay the processing of the layout as normal?