Bug 302441 [LinkedResources][CommonNavigator] When to show "Files and Folders Operation" dialog on drop
bundles/org.eclipse.ui.ide/src/org/eclipse/ui/views/navigator/NavigatorDropAdapter.java
int returnVal = dialog.getReturnCode();
                String[] returnCodes = { YES, ALL, NO, CANCEL };
                returnCode[0] = returnVal < 0 ? CANCEL : returnCodes[returnVal];
            }
        });
        if (returnCode[0] == ALL) {
			alwaysOverwrite = true;
		}
        return returnCode[0];
    }
    /**
     * This method is used to notify the action that some aspect of
     * the drop operation has changed.
     */
    public boolean validateDrop(Object target, int dragOperation,
            TransferData transferType) {
        if (dragOperation != DND.DROP_NONE) {
            lastValidOperation = dragOperation;
        }
        if (FileTransfer.getInstance().isSupportedType(transferType)
                && (lastValidOperation != DND.DROP_COPY)
                && (lastValidOperation != DND.DROP_LINK)) {
            
            return false;
        }
        if (super.validateDrop(target, dragOperation, transferType)) {
            return true;
        }
        return validateTarget(target, transferType).isOK();
    }