In GoWrite and for an SGF diagram, the colour of several or all setup stones is inverted as follows:

1. Mark stones.

2. Select a setup stones tool.

3. Double-click on one of the marked setup stones.

This procedure inverts the colour of the marked setup stones but does not affect the colour the marked other stones (created by moves). Either the black or white setup stones tool can be selected. If all stones are marked setup stones, the whole position is colour-inverted.

I found the procedure accidentally, after years of wishing such a thing would exist...

The things one can discover with clumsy fingers: a friend of mine managed to get full local access to a networked Windows 98 machine by misclicking on the logon username "What's this?" help tooltip and opening a print dialog!