Bug 197113 Project Explorer drag and drop selection not working properly
Create a new java project. Open Project Explorer. Create 2 new classes - Test1 and Test2. Close the java code editors. Select Test1.java in the project explorer. Select Test2.java by doing a mouse down only (so Test1.java still appears highlighted) then drag Test2.java into the code editor area ()- Test1.java is displayed. This only occurs in the Project Explorer, the package explorer works fine.
bundles/org.eclipse.ui.navigator/src/org/eclipse/ui/navigator/CommonViewer.java
}
	
	/* (non-Javadoc)
	 * @see org.eclipse.jface.viewers.StructuredViewer#handleSelect(org.eclipse.swt.events.SelectionEvent)
	 */
	protected void handleSelect(SelectionEvent event) {
		clearSelectionCache();
		super.handleSelect(event);
	}
	
	/**
	 * Clears the selection cache.
	 */
	private void clearSelectionCache() {
		cachedSelection = null;
	}
	
	/**
	 * Returns the current selection.
	 * <p>
	 * Note that as of 3.2.1 and 3.3, the common viewer caches its selection.
	 * Clients must not set the selection of the viewer's tree control directly.
	 * </p>
	 * 
	 * @see org.eclipse.jface.viewers.AbstractTreeViewer#getSelection()
	 */
	public ISelection getSelection() {
		if (cachedSelection == null) {
			cachedSelection = super.getSelection();
		}