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
return null;
        WelcomeItem item = (WelcomeItem) text.getData();
        StyleRange[] ranges = text.getStyleRanges();
        int currentSelectionEnd = text.getSelection().y;
        for (int i = 0; i < ranges.length; i++) {
            if (ranges[i].start >= currentSelectionEnd)
                if (item.isLinkAt(ranges[i].start))
                    return ranges[i];
        }
        return null;
    }
    /**
     * Finds the previous link before the current selection.
     */
    private StyleRange findPreviousLink(StyledText text) {
        if (text == null)
            return null;
        WelcomeItem item = (WelcomeItem) text.getData();
        StyleRange[] ranges = text.getStyleRanges();
        int currentSelectionStart = text.getSelection().x;
        for (int i = ranges.length - 1; i > -1; i--) {
            if ((ranges[i].start + ranges[i].length) < currentSelectionStart)
                if (item.isLinkAt(ranges[i].start + ranges[i].length - 1))
                    return ranges[i];
        }
        return null;
    }
    /**
     * Finds the current link of the current selection.
     */