Graph themes and related items

[Jean Brefort <jean brefort normalesup org>]

Hi,

I would like to enhance the current graph theme code. Currently, we have
two inline themes (Default (Excel like) and Guppi), and anybody can
create a custom theme as explained in the Goffice API documentation.

Custom themes have several drawbacks: they are painful to edit since
there is no GUI for that, and, worse, they are not saved with the
document, so that the rendering will not be the same everywhere.

These two issues can be fixed (I know how, but I need some time). Just
that opens a new question: what should be done if a theme embedded
inside a document has the same name than a local theme? Note that the
graph is saved with just the theme name.

1. it hides the local theme
2. it is dropped and the local theme is used
3. it is renamed on the fly to avoid hiding the local theme

It might also be possible to compare the two themes to see if they are
identical or not (might be a bit difficult, but still possible). If yes,
option 2 would be applied.

Each option has it pros and cons and I'll wait for comments before
deciding.

Best regards,
Jean