Can I safely reinstall PCManFM in Lubuntu desktop?

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http://askubuntu.com – I seem to have some problems with pcmanfm (openbox took over my desktop) and I would like to reinstall in Synaptic but it says it wants to remove (reinstall eventually) lubuntu-core, lubuntu-default settings and lubuntu-desktop. Is that safe? After installing lxde and lxde-core, uninstalling pcmanfm involves removing them too. (HowTos)