Can't group non-continuous glyphs
If the image contains white space interrupted glyphs, the tracer wrongly interprets parts of glyph as a whole by itself.
There seems to be no way to circumvent this behavior from the GUI.
This could be corrected by adding a way to select and group parts of a glyph (e.g. pressing the shift key while clicking on the glyph's parts).
Attached by is an example image of such a situation. The same problem appears if using images of complex glyphs based on more then one part.