This FAQ is based on questions from the Nokia Developer Forum
Q: Can I edit sis files in the Carbide.ui?
A: No. You can edit existing theme project directory, import project zipped or in tpf form.
Q: Can I convert bitmap format (PNG, GIF) to vector format (SVG)?
A: No. Although it is possible to embed the PNG file inside the SVG this does not convert bitmap format to the vector format (so when resizing SVG containing bitmap image inside, the image gets distorted). And besides embedded bitmaps are not supported anyway.
Q: What is the recommended SVG editor for the Carbide.ui?
A: I would say that there is not any specially preferred SVG editor. The most important thing is that the editor gets the job done. You can find links to SVG editors on the SVG page. Please note that the SVG files are converted during the edition to the SVG Tiny format, that is subset of SVG format specification.
Q: How can I extract and edit default icons from S60 3rd Edition phones?
A: Unless they are not released for public use, you cannot do it.