Bug 286949 [Browser] Bad usage of URL#equals(Object) in WebBrowserEditorInput
HEAD WebBrowserEditorInput#equals(..) calls URL#equals(Object), but the latter resolves the host of the URLs via DNS lookups, which is most of the time not what you want. You should instead compare the strings from URL#toExternalForm(). Furthermore, WebBrowserEditorInput should also override hashCode() (equal objects must have equal hash codes). Note that URL#hashCode() is also broken, so you should use URL#toExternalForm() there as well.
bundles/org.eclipse.ui.browser/src/org/eclipse/ui/internal/browser/WebBrowserEditorInput.java
url = new URL(str);
			}
			catch (MalformedURLException e) {
				String msg = "Malformed URL while initializing browser editor"; 
				WebBrowserUIPlugin.logError(msg, e);
			}
		}
		String id = memento.getString(MEMENTO_ID);
		String name = memento.getString(MEMENTO_NAME);
		String tooltip = memento.getString(MEMENTO_TOOLTIP);
		
		WebBrowserEditorInput input = new WebBrowserEditorInput(url, style, id);
		input.setName(name);
		input.setToolTipText(tooltip);
		return input;
	}
	/**
	 * Tests to see if two input objects are equal in the sense that they can share an
	 * editor.
	 * @return true if the url and browser id are equal and the style bits are compatible
	 */
	public boolean equals(Object obj) {
		if (this == obj)
			return true;
		if (!(obj instanceof WebBrowserEditorInput))
			return false;
		WebBrowserEditorInput other = (WebBrowserEditorInput) obj;
		if (url != null && !url.equals(other.url))
			return false;
		return canReplaceInput(other);