Merge paragraphs of different non-Default/Plain Layouts

[Daniel]

I am always a little stumped that it is not allowed to merge two 
paragraphs by pressing backspace (delete) at the first (last) position 
of a paragraph where there is another layout in the previous (next) 
paragraph.

I think I found the passage in the source which sound as if this is an 
important idea:

	// FIXME: Do we really not want to allow this???
	// Pasting is not allowed, if the paragraphs have different
	// layouts. I think it is a real bug of all other
	// word processors to allow it. It confuses the user.
	// Correction: Pasting is always allowed with standard-layout
	// or the empty layout.
	else if (par.layout() == prevpar.layout()
		 || tclass.isDefaultLayout(par.layout())
		 || tclass.isPlainLayout(par.layout())) {
		cur.recordUndo(prevcur.pit());
		mergeParagraph(bufparams, plist, prevcur.pit());
		needsUpdate = true;
	}

Unfortunately, I don't see why it is such a bad idea to merge in this 
case. Maybe someone can enlighten me. I find it hard to train my brain 
to consider the layout circumstances when trying to merge paragraphs. 
Hence, I would suggest to remove the check.

Best,
Daniel