Problem: FileMaker offers common formatting in all input fields (bold, italics, underline, font size, color and so forth). While this is nice in some circumstances - FM as a correspondence tool for example or formattable notes fields - it is unwanted in pure data fields. In most cases users will not format those fields either, so it is no problem if you can but don´t do it.
But with the clipboard copying formatted text you sometimes get what you don´t need and don´t want. Of course you can hit Alt to only paste the pure text, but what if people don´t know about this trick or don´t use it. You get formatted text which might be even unreadable in your data field. At least it looks awful or funny on your layout. And there is no "easy" way to unformat this text again.
Solution: Option in the layout inspector to mark fields as "non formattable", ie. only holding pure text always shown in the given CSS styling. In these fields no formatting options are offered and pasted text automatically looses all formatting.
On the other hand FM GO and webdirect should learn to handle formatted text to be compatible with FM Pro.