Return DELTA if DELTA lines can be added to WINDOW.
WINDOW must be a valid window and defaults to the selected one.
Optional argument HORIZONTAL non-nil means return DELTA if DELTA
columns can be added to WINDOW. A return value of zero means
that no lines (or columns) can be added to WINDOW.
This function looks only at WINDOW and, recursively, its child
windows. The function `window-resizable' looks at other windows
as well.
DELTA positive means WINDOW shall be enlarged by DELTA lines or
columns. If WINDOW cannot be enlarged by DELTA lines or columns
return the maximum value in the range 0..DELTA by which WINDOW
can be enlarged.
DELTA negative means WINDOW shall be shrunk by -DELTA lines or
columns. If WINDOW cannot be shrunk by -DELTA lines or columns,
return the minimum value in the range DELTA..0 by which WINDOW
can be shrunk.
Optional argument IGNORE non-nil means ignore restrictions
imposed by fixed size windows, `window-min-height' or
`window-min-width' settings. If IGNORE equals `safe', live
windows may get as small as `window-safe-min-height' lines and
`window-safe-min-width' columns. If IGNORE is a window, ignore
restrictions for that window only. Any other non-nil value means
ignore all of the above restrictions for all windows.