Currently, multigrid mouse drag positions are handled incorrectly if the
drag event is not in the top left grid. Fix this by not adjusting the
position of the event in jump_to_mouse.
related: #15091
When create tab, win_hide sent to new tab and new tab's previous tab.
So, if created tab that not next tab (eg. $tabnew cmd),
send win_hide to not current tab, and fixed this.
It is perfectly fine and expected to detach from the screen just by
the UI disconnecting from nvim or exiting nvim. Just keep detach() in
screen_basic_spec, to get some coverage of the detach method itself.
This avoids hang on failure in many situations (though one could argue
that detach() should be "fast", or at least "as fast as resize",
which works in press-return already).
Never use detach() just to change the size of the screen, try_resize()
method exists for that specifically.
Callers can instead specify `args_rm={'--headless'}`.
TODO: should `nvim_argv` have "--headless" by default? Need to inspect
some uses of spawn(nvim_argv) ...
