How can I get some display feature (such as bold lines) in dotty or lneato?
Dotty and lneato have not really changed for many years. Therefore, there are myriad features available in Graphviz which they cannot handle. In some cases, you can use Grappa or webdot for display instead of them. For example, Grappa has generalized polygons (node [shape=polygon]) that dotty lacks. There are additional interactive viewers available. For example, see Graphical Interfaces and Viewers. If you are using MacOSX, the Mac version of Graphviz has a highly recommended GUI. Alternatively, for some applications, it is sufficient to use the layout programs to create a postscript, jpeg or svg file and then use one of the generic viewers for those formats. If the display attribute that you need isn’t there already, in dotty, there’s probably no easy way to do it except by rolling up your sleeves and hacking the dotty code (a lefty script) that interprets and renders graphical attributes. This is problematic for the same reason as above: there’s no universal low-level driver layer s