Usability of symbol definition interface

[krticka]

I am currently struggling with point symbol definition and think that usability can be improved in following way:

1. Provide option to show map symbol coordinate grid
2. Editing is currently difficult and confusing, if you select row with coordinates, nothing is selected in window with symbols, too complicated to change part of the object. Provide similar editing as in map window, so use rectangle for object selection and vertices for shape change.