// I do not know why this is the right way, but with the below cairo_move_to it seems to be centered (horiz. and vert.)
cairo_move_to(c, -r1.x/2+g_tooltip.bg->border.width+g_tooltip.paddingx, -r1.y/2+g_tooltip.bg->border.width+g_tooltip.paddingy);
pango_cairo_show_layout (c, layout);
// I do not know why this is the right way, but with the below cairo_move_to it seems to be centered (horiz. and vert.)
cairo_move_to(c, -r1.x/2+g_tooltip.bg->border.width+g_tooltip.paddingx, -r1.y/2+g_tooltip.bg->border.width+g_tooltip.paddingy);
pango_cairo_show_layout (c, layout);