width attribute for histograms

[Wolfgang]

Right now it is possible to have plots resembling histograms by choosing as plot style VAL_VERTICAL_BAR.

However, at present the width of these bars can only be adjusted by changing the line thickness in pixels (ATTR_PLOT_THICKNESS)

From a users point of view it would be more useful having the possibility to specify the width in units of the x axis.

Explanation: Say one is plotting an xy graph, with the data equally spaced and in incremetns of 1. If the x scale is 0-100 there would be 100 thin lines which may be appropriate in most cases. If the x scale is 0-5 there would be only five thin vertical lines. This appearance is very much different from what one would expect from an histogram. The suggestion is to set the width of the histogram bars to say +/- 0.4 x units, then there would be nice bars ranging from 0.6-1.4, 1.6-2.4, etc. in the case of an axis scale of 0-5, and the width of the bars would shrink accordingly if the axis scale is 0-100; in this case, there would be 100 rather thin lines resembling more or less the current appearance.

So in effect this suggestion is about an automatically adjusting line width (right now it is not possible to implement it manually because the line width is specified in pixels rather axis untis and is also limited to a maximum of 32 pixel.)

One step further could be to draw rectangles instead of lines with the possibility to independently choose line color and fill color.