Thanks all for your help, very much appreciated!
@Misha: there is a paper glued to the back of the frame, and I am not keen on removing that; even if there is a date, it would probably not give a clue -- the painting could be contemporary to the glass pictured, or someone painted grandma's vases in the many decades later

@m: looks like a similar colour and decor, well spotted. The lines on "my piece" seem to be more regular, though.
@waltl2: I think the Bohemia attribution is quite solid, but I will look into French Art Nouveau glass, too...
Michael