-\fBKEY_MOUSE\fP is mentioned in XSI Curses, along with a few related
-terminfo capabilities, but no higher-level functions use the feature.
-The implementation in ncurses is an extension.
+The behavior of \fBgetch\fP and friends in the presence of signal
+handlers is unspecified in the SVr4 documentation and X/Open Curses.
+Under historical curses implementations,
+it varied depending on whether the operating system's dispatch of a
+signal to a handler interrupts a \fBread\fP(2) call in progress or not,
+and also
+(in some implementations)
+whether an input timeout or non-blocking mode has been set.