Overlapping bars

["DIMITRIS TSOKAKIS" <TSOKAKIS@xxxx>]

>From the first sight the following codes are producing the same 
result:
/*first*/
freq = 1;
s=sin( cum( freq/10 ) );
a=0.5*sin( cum( freq/10 ) );
graph0=a;
graph1 = s; 
graph0style=2;
graph1style=2;
graph0barcolor=3;
graph1barcolor=7;

/*second*/
freq = 1;
s=sin( cum( freq/10 ) );
a=0.5*sin( cum( freq/10 ) );
graph1=a;
graph0 = s; 
graph0style=2;
graph1style=2;
graph0barcolor=3;
graph1barcolor=7;

In the first we can see two overlapping sinusoidal bargraphs, one 
yellow and one greyblue.
In the second, yellow bars disappear.
It is not tricky.
There is a priotity in graphing overlapping bars. 
According to Mr Janeczko valuable hint "the graph lines are drawn in 
a reverse order graph0 is drawn the last and it covers previous graph 
lines"
An interesting application of this priority was used in #2182 mail: 
Using graph0barcolor=0 in the "first" , where 0 is no color, i.e. 
background color, we can have "floating" bars.
Use it whenever is appropriate.

Dimitris Tsokakis