MyGUI font scaling

I've made a layout with StaticText using my own png font (quite big letters). Yet in 1600x1200 everything looks nice, but when I change the resolution the text won't scale and doesn't fit in the screen. The letters are just too big. I've been searching a lot but couldn't find the solution.

Is it possible to rescale the StaticText depending on screen resolution? I've tried things like align STRETCH, but it doesn't work.
If MyGUI doesn't support this, maybe there's a way to get to the font texture in the code and rescale it independently from MyGUI?

Thanks in advance

widget->setFontHeight(resolution / coef);