Font and formatting of side strips and x axis label

[mevers]

Dear ggbio developers.

Is there a possibility to change the font of the side strip text?

For example, I have two tracks

tracks <- tracks(
    Annotation = gg1,
    Coverage = gg2,
    xlab = "x axis label");

In can set track-specific fonts in gg1 and gg2 individually, e.g. through theme(family = ...). However, I don't know how to change the font of the text in the side strips (i.e. "Annotation" and "Coverage"); I also don't know how to change the font family/size/face of the common x axis label.

Is there an easy way to set a global font family which gets passed down to other track-specific text objects (e.g. axis titles, title, subtitle, caption, etc.)?

Thanks, Maurits