This is the screenshot of the similar Excel program that now is written in OpenOffice. The conversion from Excel to OpenOffice was actually simpler than I thought. At first, there are errors. But after closer look, I realise not all the formulas can be directly converted. It was not really the problem of OpenOffice as my codes actually contain very specific way of reading some information and this cannot be directly translated to OpenOffice. After some checking, the errors were corrected and the OpenOffice program output the same results as the Excel program (as expected).
What is difficult is the macro for excel cannot be directly convert to OpenOffice macro. This is the painful part for me, as there are not many books and resources on writing Macro for OpenOffice and the process is also much more tedious than VBA. After 2 weeks of on and off writing, main part of the Macro was in shape but one crucial problem was bugging me, ie how to unload the menu after popping up. I decided to stop for a week and send the code to a friend who are familiar with OpenOffice to take a look. He is helpful but can't really give the solution. Then suddenly, I come across a website and briefly talk about the similar issue (not exactly but was along that line). I copy the idea and "hola", it solved. Now the macro works exactly like Excel program.
I am waiting for the release of OpenOffice 3.2 for testing the program further.