Setting the coordinate system and then the centre position doesn't work correctly if the image is not active

[confluence]

As described in #116. This is one of several cases where the scripting interface performs an operation on an inactive image which would not be possible through the browser GUI, and this causes an unexpected problem. In this case, we may need to provide access to the frontend's AST object so that the scripting interface can set certain AST properties explicitly, but this needs more investigation.

[confluence]

This may be fixed in the latest frontend.