This thread might also be helpful:
http://answers.ros.org/question/9665/test-for-when-a-rospy-publisher-become-available/

The question is specifically about python, but i think the root cause is ROS specific, not language specific.

ros send message on startup doesn't seem to work
Whats the recent status of TiKz support in ConTeXt MkIV? I'm asking because
in pgfmanual 2.10 on page 25 it says: 


  Note that pgf/TikZ is not supported by recent ConTEXt versions (like mark IV, the LuaTEX-aware part of ConTEXt).


I tried the following example but it doesn't work as expected.

\setupcolors[state=start]
\usemodule[tikz]   

\starttext

\starttikzpicture
 [node distance=4cm,
    place/.style={circle,draw=blue!50,fill=blue!20,thick,
                 inner sep=0pt,minimum size=6mm}]

    \node[place] (wat) {};
  \node[place] (wag) [below=of wat] {};

\stoptikzpicture

\stoptext


No matter how big the node distance=4cm is, the circles are overlapping with an offset of approximately  0.5cm. 

ConTeXt version: mtx-context     | current version: 2012.05.22 16:12 
