The previous `attachCustomWheelEventHandler(() => false)` killed scrolling
outright. xterm's `bindMouse` consults that handler in BOTH wheel paths — the
one that emits a real SGR mouse report and the fallback that turns a notch on
an alt-screen buffer into ESC[A/ESC[B — so a blanket false also blocked tmux's
own wheel scrolling (tmux runs with `mouse on`, i.e. tracking is active).
Now the handler returns false only for the exact bad case: no wheel tracking
AND an alternate buffer. `x10` counts as untracked because that protocol
reports button presses only, never the wheel, so xterm takes the emulation
path for it too.
nntrivi2001
77ca6e0188