For my application I do not like the vertical axis labels aligned vertically, so I tried using gtk_databox_ruler_set_text_orientation to turn them round. This works, but the labels are all in the wrong place.
Looking at the code for v0.9.2.0, I think the problem is in lines 1438 and 1440 of gtkdatabox_ruler.c where the Y offset is calculated from the X size:
if (ruler->priv->text_orientation == GTK_ORIENTATION_HORIZONTAL) /* if ticks are present, then draw a little higher */ y_loc=pos - logical_rect.width*2/3; /* horizontal text y alignment */ if (ruler->priv->text_orientation == GTK_ORIENTATION_HORIZONTAL & !ruler->priv->draw_ticks) /* if ticks aren't present, draw a little lower */ y_loc=pos - logical_rect.width/3;
If text is horizontal, then Y offsets should be based on logical_rect.height, not width!