Hi again Beatrix,

In the latest version of the patch I am preparing, if you do

    (add-hook 'c-mode-hook
	      (lambda ()
		(setq-local electric-layout-rules
			    '((?\{ . before})
                              (?\{ . after)
			      (?\{ . after-stay)))))

You should arive at Allman C-style electric layouts.  So typing
int main () <spaces> then brace should give you:

int main ()
{
  <cursor here>
}

I attach the two patches for convenience, which you can also find in the
scratch/fix-33794-extend-electric-layout-mode branch.

João