> From: "Lennart Borgman" <[EMAIL PROTECTED]> > Date: Sun, 27 Feb 2005 18:57:08 +0100 > > I am trying to understand the implementation around hourglass cursors. When > I look through eval.c, fns.c, keyboard.c, lread.c and minibuf.c I see in > many places something like: > > #ifdef HAVE_X_WINDOWS > if (display_hourglass_p) > cancel_hourglass (); > #endif > > Is this really correct?
Yes, I think so. > It looks like displaying an hourglass cursor should only happen if x > windows is available. What other systems? If you refer to Windows, then please see w32fns.c, where the timer-related hourglass code is ifdef'ed away (probably because Windows doesn't emulate well Posix timers that raise asynchronous signals). The Windows implementation of hourglass cursor, if I understand it correctly, is synchronous, i.e. the redisplay code and the idle loop set and reset it. Of other non-X ports, the MSDOS port doesn't support this feature at all (you cannot change the Windows mouse pointer shape from a DOS program running on Windows, and doing so on plain DOS involves undesirable complications). As for MacOS X, I don't know. > Maybe it would be better to remove these ifdefs and require every Emacs > implementation to compile the lines? Does not most systems actually have the > possibility to display hourglass cursors? If they do not could the > implementation not just supply some dummies for the required functions? That'd not be a good idea, I think: firing SIGALRM signals by the timers complicates things (e.g., you get to handle the problem of interrupted system calls), so it shouldn't be done without a good reason. _______________________________________________ Emacs-devel mailing list Emacs-devel@gnu.org http://lists.gnu.org/mailman/listinfo/emacs-devel
