5.2.30 Overlay and manipulate overlapped windows

Procedure: overlay srcwin dstwin

Procedure: overwrite srcwin dstwin

The overlay and overwrite routines overlay srcwin on top of dstwin. scrwin and dstwin are not required to be the same size; only text where the two windows overlap is copied. The difference is that overlay is non-destructive (blanks are not copied) whereas overwrite is destructive.

The return values are unspecified.

Procedure: copywin srcwin dstwin sminrow smincol dminrow dmincol dmaxrow dmaxcol overlay

The copywin routine provides a finer granularity of control over the overlay and overwrite routines. Like in the prefresh routine, a rectangle is specified in the destination window, (dminrow, dmincol) and (dmaxrow, dmaxcol), and the upper-left-corner coordinates of the source window, (sminrow, smincol). If the argument overlay is #t, then copying is non-destructive, as in overlay.

Returns #t on success or #f on failure. #f could indicate that some part of the window would be placed offscreen.