Bug 117925 [Intro] Misleading exception message in WelcomeEditor.init()
... it says it expects an IFileEditorInput, but it actually checks for WelcomeEditorInput. Suggested patch appended.
bundles/org.eclipse.ui.ide/src/org/eclipse/ui/internal/ide/dialogs/WelcomeEditor.java
GridData gd = new GridData(GridData.FILL_BOTH);
        messageLabel.setLayoutData(gd);
        
        Label titleImage = new Label(titleArea, SWT.LEFT);
        titleImage.setBackground(background);
        titleImage.setImage(PlatformUI.getWorkbench().getSharedImages()
                .getImage(IDEInternalWorkbenchImages.IMG_OBJS_WELCOME_BANNER));
        gd = new GridData();
        gd.horizontalAlignment = GridData.END;
        titleImage.setLayoutData(gd);
        return titleArea;
    }
    /**
     * The <code>WorkbenchPart</code> implementation of this 
     * <code>IWorkbenchPart</code> method disposes the title image
     * loaded by <code>setInitializationData</code>. Subclasses may extend.
     */
    public void dispose() {
        super.dispose();
        if (busyCursor != null)
            busyCursor.dispose();
        if (handCursor != null)
            handCursor.dispose();
        if (this.colorListener != null) {
            JFacePreferences.getPreferenceStore().removePropertyChangeListener(
                    this.colorListener);
        }
    }
    /* (non-Javadoc)
     * Saves the contents of this editor.