I have a button script that changes the size of a selection in a text field. 

This is it:

Insert Calculated Result [ TextSize ( Middle ( Get ( ActiveFieldContents ) ; Get ( ActiveSelectionStart ) ; Get
( ActiveSelectionSize ) ) ; $size ) ] 

A problem with this is that if the selection begins with styled characters (bold, underlined, etc) then the entire resized area becomes styled. If there is at least 1 unstyled character before the first styled one, then all styled and unstyled characters remain as they were. What is missing from the calculation? 

I have tested this on my own and I am not sure if this is a bug or an intended behavior. The Insert Calculated Result[] script step behaves in this aspect the same as the Replace() function. The inserted text takes on the style of the text at insertion point (in addition to any style/s it may have on its own). Perhaps they (FMI) thought that would be helpful.

I'm not sure what the reason would be for intending this behavior. It is clearly an annoying behavior. The only workaround is to insert an unstyled character in front of the selection, make the change then remove the extra character.