Hello Tiago, It looks like the commit "e3c57b270640f9948d7fda7459376eb40d600719" has introduced a bug in the cairo_draw that I have fixed on my machine but I would like to create a merge request for the same. In short the following code throws the error: import graph_tool.all as gt g = gt.collection.data['karate'] gt.graph_draw(g, vertex_pen_width=5, vertex_color = 'k', output='test.png') The error is: Traceback (most recent call last): File "/usr/lib/python3/dist-packages/graph_tool/draw/cairo_draw.py", line 1145, in graph_draw x, y, w, h = fit_view TypeError: cannot unpack non-iterable bool object During handling of the above exception, another exception occurred: Traceback (most recent call last): File "test.py", line 4, in <module> gt.graph_draw(g, vertex_pen_width=1, output='test.png') File "/usr/lib/python3/dist-packages/graph_tool/draw/cairo_draw.py", line 1153, in graph_draw x, y, zoom = fit_to_view_ink(g, pos, output_size, vprops, File "/usr/lib/python3/dist-packages/graph_tool/draw/cairo_draw.py", line 1345, in fit_to_view_ink eprops = dict(eprops, pen_width=min_lw(eprops.get("pen_width"))) File "/usr/lib/python3/dist-packages/graph_tool/draw/cairo_draw.py", line 1342, in min_lw lw = max(lw, 0.1) TypeError: '>' not supported between instances of 'float' and 'NoneType' I tracked the error and it looks to me that in the function ``min_lw`` which itself is inside ``fit_to_view_ink``, if user passes ``pen_width`` only for edges or only for vertices, the other becomes ``None`` and should be handled properly. I could fix this by adding an extra ``if`` condition as follows: # work around cairo bug with small line widths def min_lw(lw): if isinstance(lw, PropertyMap): lw = lw.copy() x = lw.fa x[x < 0.05] = 0.1 lw.fa = x else: if lw == None: lw = 0.1 lw = max(lw, 0.1) return lw I would like to push this change upstream, but you seem to have denied my access request so I can't create a merge request. If you think this is fine, could you make the change? In general, how do I fix bugs if/when I find them if access on git.skewed is not available? Thanks and regards, Snehal Shekatkar