> addsomething like > > Style Theorem > Margin First_Dynamic > LatexType Environment > LatexName theorem > #DependsOn TheoremStyle > NextNoIndent 1 > Align Block > AlignPossible Block, Left > LabelString "Theorem #: > Font > Shape Italic > Size Normal > EndFont > LabelFont > Shape Up > Series Bold > EndFont > End > > to your favourite .layout.
It works perfectly, except the fact that the LabelString is not visible on LyX window.
