I should think it would be very difficult if you mean the type where the whole window is changed around. I've messed about with some controls that do that on vb6, and without exception they didn't work reliably and/or had various horrible problems.
If you just want to change colours and fonts, that is ok. I have programmes where I have used controls tags to control the process, holding values like 'light' and 'dark'. Then use the colour and font dialogues to create values. Then loop through the controls collection and alter fonts and colours. There are a few fiddly bits, but it looks ok.
I had to limit the font size selection or things just didn't fit. Also I resized labels and text boxes to suit the new font. You need to think about this as you would run the colour and font changer on form load when text boxes are mostly blank and it is easy to end up with zero width boxes. Peter Meachem
peter@accuflight.com