Mmm tesselations. Are those kangaroos? http://inkscape.org/screenshots/gallery/inkscape-0.41-CVS-linux-tiles1.png
I don't know :) This was the first tesselation I ever made, that's why it's so rather awkward :) Took me about half an hour in total to draw it.
GTK has stock buttons for Reset and Remove which I hope would be used and although it is not ideal I would use OK instead of Create so as to use a Stock button and keep plug-ins as consistant as possible (although I realise this is probably not implemented as a plug-in).
I don't like the "OK", "Create" is more descriptive. And using icons for some of the buttons and not others would look weird.
I expect that at some point you might want to add the ability to save Presets at the top of every plug-in dialog above the tabs something like this:
Presets [ dropdown list [v] [ Save...]
Yes, presets are a good idea. Some other things I may do sometime for this dialog:
- watching the current selection and enabling/disabling the Create, Remove, and "Use saved bbox" correspondingly
- visualizing the saved bbox on the canvas (e.g. red) when the dialog is open
- a preview image for each symmetry, using some standard simple shape