(I don't know if this is unique to 2.51 beta 29)
Drum parts often have dotted-eighth/sixteenth patters repeated measure after measure after measure. It's customary to use a single bar repeat sign. I use Lawrie's SwingDings \ character as a text entry, and either set the notes in repeated bars to stem-length=zero with blank noteheads, or simply set the notes to visibility=never.
If I use zero-stem length and blank noteheads, the dotted note dots still display. They shouldn't.
On playback, the coloured note chase on playback follows notes set to visibility=never, but not notes that are set to stem=zero/notehead=blank.
While stem=zero/blank notehead is used for things that visibility=never isn't, the note-chase and extension dots should be the same.