enterAltBufferWithoutCursorSave
Switches to the alternate screen buffer without saving the primary cursor state.
This supports the older xterm alternate-screen modes:
CSI ? 47 hswitches to the alternate buffer without clearing it.CSI ? 1047 hswitches to the alternate buffer and clears it first.
The alternate buffer has no scrollback history. Re-entering while already active is a no-op.
Parameters
clearBeforeEnter
whether to clear the alternate grid, reset its margins, home its cursor, and clear its saved-cursor slot before entry.