Idea Window
In Sibelius there is an "Ideas" window where you can save fills, beats, grooves etc. to use in later scores or in the same score at a later place. MuseScore should implement something similar, so that if you have a specific piece of a score you feel might be useful later, you can use this without saving it in a completely separate file.
Comments
I find it just fine to save a seperate file and then open it in a new tab in MuseScore but for those who want a quick and efficient work flow I can see how something like this would make sense.
In reply to I find it just fine to save… by Piotr Barcz
In Musescore 3 you can have two documents open and view them side by side if your screen is large enough - you can also copy and paste between them. See https://musescore.org/en/handbook/3/viewing-and-navigation#display