[Libreoffice] Need help with symbols in object dialog of chart data series

Hi all,

I want to add further standard symbols for data points in line charts 
and xy-charts for to provide all standard symbols that are defined in 
ODF1.2.

At the current stage of my developing, I can already select the new 
symbols, they are shown as designed in the chart, they are saved to file 
and reloaded. But now I am stuck with the data series (data point) 
object property dialog. Perhaps someone can give me a hint?

(1)
There is a drop-down menu "Select" in the object property dialog of a 
data series or data point. In the drop-down menu is an item "Symbols". 
It opens a list of the implemented standard symbols. The list itself is 
filled correctly with all standard symbols including the new ones and I 
can select them. But some of the symbols are displayed at a wrong 
position. Where is the code that paints the symbols to this list?

(2)
There is a preview of line and symbol in the lower part of the mentioned 
dialog. The symbols are not displayed in original ratio, but stretched 
to a square. As a result, the new 'horizontal bar' and 'vertical bar' 
look like a square in this preview. In the chart itself the new symbols 
are painted correctly. Where is the code for painting this preview?

Kind regards
Regina