I would like to have more than 2 levels of layers in my geoexplorer.
I use groups, inside of "gxp_layertree", but is it possible to get more groups e.g. a tree of 3 or 4 levels?
Not possible without writing custom code. See this old piece of code for some inspiration: https://github.com/boundlessgeo/Tridex/blob/master/app/static/script/app/Tridex/NestedLayerTree.js