no edge or background to allow alpha blending
@@ -363,7 +363,7 @@ class Icon:
xycoords=xycoords,
box_alignment=box_alignment,
boxcoords='offset points',
- bboxprops={'edgecolor': 'w', 'facecolor': 'w'},
+ bboxprops={'edgecolor': 'none', 'facecolor': 'none'},
arrowprops={
'linewidth': linewidth,
'color': tickline_color,
