You can simulate a speedbar-like layout within ONE frame by doing the following:
ecb-layout-nameto layout name “left9”, “left12”, “left13” or “left14” dependent to what you like.
ecb-toggle-layout-sequenceand toggle very fast between several layouts by
ecb-toggle-layout. See the doc-strings!
ecb-show-sources-in-directories-bufferto not nil if the chosen layout (see 1. and 4.) contains a directories-tree-buffer.
But not only simulating speedbar is possible but also full integrating it into the ECB and the ECB-frame, See Integrating speedbar.