If I play with the line font, I still don't have the desired visual for the components that are underneath, these are always in hidden lines, when they should be seen in strong lines (and I don't want to play with all line fonts...
If the configurations (but this seems to me to be the only solution to have mixed line parts in the MeP) are too heavy to manage, you can try the "Display State" linked or not to the configuration. This allows for the management of display types (shaded, wireframed, dotted), hidden-shown and transparency component by component (very fast loading time compared to configuration change). You can have as many display states as you want for the same configuration. Then, in your MeP, you specify which display state you want for each view.
On the other hand, if you absolutely want mixed strokes on some pieces, I'm afraid that the solutions given above are the best!
Otherwise, but this is a little more work, I have already done by putting 2 different views on each other by freezing the position so that it does not move in relation to each other, in the first one you put the pieces in strong line, in the other, the pieces in mixed lines.
I was on solidedge before being on solidworks and there are features that I regret! This one is one of them.
It is for assembly drawings that the problem arises. An example:
I design welding tools for any chassis. On my overall plan, I need to see my tools first - in strong (and/or hidden) lines, but I also need to see the "envelope" of the chassis to see how it is positioned. Only if my chassis is in strong lines, I can't see anything of my tools anymore... Hence the need to see my chassis as a "ghost" without altering the readability of my tools.
It's funny because it's something very common on other software.
@benoit.guerel: there is the envelope function to do this in the 2013 and 2014 versions, you can create an envelope of a sub-assembly underneath you can only do it on the parts.
This function exists in the component properties (see attached image on SW2013)
Edit: Damn it doesn't work as I hoped (I was convinced that I managed to be in mixed line in the drawing of an envelope component)....