The meaning of “cut and paste” is less obvious for a music editing program than it is for something like a word processor in which the letters and words go in a simple linear order. Accordingly, Rosegarden's Notation editor offers several different types of Paste operation, as well as separate Cut and Cut and Close functions.
Requires an existing gap (containing nothing but rests) of enough duration to completely contain the clipboard's contents. The contents are pasted into the gap. If there is no gap long enough, the paste is not carried out.
This is the default paste type.
Erases enough events to make a gap long enough to paste into, and then pastes into that. The pasted events therefore completely replace any existing ones in the time covered by the paste.
The opposite of Cut and Close. Makes room for the paste by moving all of the subsequent events further towards the end of the composition.
Carries out a paste in the way that it would happen if you entered each of the notes in the clipboard yourself using the notation editor: if there are other notes overlapping with them, the new or existing notes will be split into ties appropriately.
Carries out a paste in the way that it would happen if you entered each of the notes in the clipboard yourself using the matrix editor: the notes presently in the way of the paste will be ignored, allowing the new notes to overlap arbitrarily with them.
All of these take effect at the current position of the insert cursor on the current staff. To choose between the various paste types, use the Paste... menu option (with dots) on the Edit menu.