Question

The following is when using the drag and drop library from here:

http://code.google.com/p/gwt-dnd/

When placing an absolute panel inside a relative panel, it appears to disable the drag ability. A simple example:

    private AbsolutePanel leftPanelTree = new AbsolutePanel();     private HorizontalPanel drawingAppPanel = new HorizontalPanel();     private VerticalPanel leftPanel = new VerticalPanel();     private VerticalPanel rightPanel = new VerticalPanel();     private Label rightSideFiller = new Label('Right Side');     private Label leftSideFiller = new Label('Left Side');     private Image newImage = new Image('images/link.gif');     private PickupDragController newDragController =          new PickupDragController(leftPanelTree, true);          public DrawingApplication() {                 initWidget(drawingAppPanel);                  newDragController.makeDraggable(newImage);                 leftPanelTree.setWidth('300px');                 leftPanelTree.setHeight('200px');                 leftPanelTree.addStyleName('panelBorderTest');                 leftPanelTree.add(newImage, 1, 1);                  drawingAppPanel.setWidth('100%');                 drawingAppPanel.setHeight('100%');                 drawingAppPanel.setBorderWidth(2);                  drawingAppPanel.add(leftPanel);                 drawingAppPanel.add(rightPanel);                  leftPanel.setBorderWidth(2);                 leftPanel.setHeight('100%');                 leftPanel.setWidth('100%');                 leftPanel.add(leftSideFiller);                 //leftPanel.add(leftPanelTree);                  rightPanel.add(rightSideFiller);         } 

If, however, I add the image to RootPanel (and change the boundary panel accordingly) or add the absolute panel to the RootPanel directly then drag capability works. Am I missing something here?

Answer 1

The problem wasn’t in my code after all, there is a documented issue with calling RootPanel.get().clear(); which causes this library to basically not function. There is a fix available under this issue here:

http://code.google.com/p/gwt-dnd/issues/detail?id=55

but it was not easy to find. Hopefully this will be patched in a future version if there is one.