Also remove duplicate import from the XMLMonoPrint sheet (unnamed default sheets stay applied when switching to alternates, only named are unapplied). Additionally fix some regressions from bug 379683: * top-level collapsed and uncollapsible elements weren't monospaced in monospace style. * top-level uncollapsible elements weren't indented. * there was an extra space between PIs and their expander control. Based on prototype by bgrins. MozReview-Commit-ID: 2Pikm41FMWY