Calculate MText line spacing factor

Hi, I hope someone can help me with the following problem:
Working at a CAD-application implementing several AC-features I got big
problems with the correct allignment of MText. the problem occures if the line space style is "at least" and when i have to calculate the correct linespaces between the lines 'manually'. So does anyone know a correct formula to get the linespacing if text size changes between two or in one line according to the initial textsize the maximum line sizes and the size of the last item in a line? I assume also that the linespacing of the line before must take part in such a formula. AC-reference say it would be 1.66 * linespacefactor * (size of the characters) but this only fits if the textsize is never changing. I would be very thankfull for any hints or solutions.
Thanks in advance
Thomas Cebulla
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