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comparison src/select-x.c @ 2629:140bb0f4da00

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[xemacs-hg @ 2005-03-02 18:31:55 by aidan] Wrap call to XtRegisterDrawable with check that XtWindowToWidget gives NULL, document why.
author aidan
date Wed, 02 Mar 2005 18:31:57 +0000
parents cf6ef27aa9a7
children 2b1e7cb9ae2c
comparison
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2628:63a49b9b070c 2629:140bb0f4da00
543 543
544 /* Tell Xt not to drop PropertyNotify events that arrive for the 544 /* Tell Xt not to drop PropertyNotify events that arrive for the
545 target window, rather, pass them to us. This would be a hack, but 545 target window, rather, pass them to us. This would be a hack, but
546 the Xt selection routines are broken for our purposes--we can't 546 the Xt selection routines are broken for our purposes--we can't
547 pass them callbacks from Lisp, for example. Let's call it a 547 pass them callbacks from Lisp, for example. Let's call it a
548 workaround. */ 548 workaround.
549 XtRegisterDrawable(display, (Drawable)window, widget); 549
550 The call to wait_for_property_change means we can break out of that
551 function, switch to another frame on the same display (which will
552 be another Xt widget), select a huge amount of text, and have the
553 same (foreign) app ask for another incremental selection
554 transfer. Programming like X11 made sense, would mean that, in that
555 case, XtRegisterDrawable is called twice with different widgets.
556
557 Since the results of calling XtRegisterDrawable when the drawable
558 is already registered with another widget are undefined, we want to
559 avoid that--so, only call it when XtWindowToWidget returns NULL,
560 which it will only do with a valid Window if it's not already
561 registered. */
562 if (NULL == XtWindowToWidget(display, window))
563 {
564 XtRegisterDrawable(display, (Drawable)window, widget);
565 }
550 566
551 prop_id = expect_property_change (display, window, reply.property, 567 prop_id = expect_property_change (display, window, reply.property,
552 PropertyDelete); 568 PropertyDelete);
553 569
554 XChangeProperty (display, window, reply.property, DEVICE_XATOM_INCR (d), 570 XChangeProperty (display, window, reply.property, DEVICE_XATOM_INCR (d),