apply style to group
let's imagine a style composed of two line aspects: a white one of 2 pt and a black (lower) one of 6 pt.
The line thus composed has the appearance of two black parallel lines. Now imagine crossing two lines with this aspect: one is superimposed on the other, and at the intersection the top line is not broken. But if I could apply the style to the line group then in the intersection you would have a real intersection and all the lines would break. This is great when, for example, we draw a path
Hm, I think there's a little bit of inconsistency here:
When you select a group, you can change all the members at once by selecting another colour, or changing the stroke etc. These changes are "passed on" to the members. But when you want to give all the members the same style, you have to select each one of them separately. It does not work if you only select the group.