Eirik -
Having the ability to selectively display or hide text has been discussed - and requested - numerous times. Changing the Opacity is a very kludgy work around with limited value. Working with your example - if you have a large score with 20 instruments you have to go to each instrument and “hide” the text. Then if you are exporting to PDF you have to remember to export in color instead of black & white = otherwise your “hidden” text is displayed on the PDF/.
It gets worse, suppose you have a preliminary reading of a piece - but you know it needs more work. So you just want to write a note to yourself - “extend section C another 4 bars” - but you don’t want that to appear on any distributed scores. You have to “hide” it on all parts and the full score. BUT - there is no handle to your “hidden” text - so after you distribute the preliminary scores you have to remember exactly where you put that “hidden” text to make it visible.
If you’re curious, there’s a whole different discussion here: Steinberg Forums