A full-screen app enables mouse reporting once, at startup. A client
attaching later never saw those sequences, so the web terminal read the
pane as a plain alternate screen with mouseTrackingMode "none" and its
touch and wheel gestures had nowhere to go — scrolling did nothing in a
browser opened after the session started.
Read the pane's mouse flags in the same display-message call and emit
the matching DECSETs ahead of the screen content. tmux expands an
unknown format name to the empty string, so the parser only trusts the
mouse tail when every field is present.
Closes#128
Miguel Palhas
eb9b4b4ae8