Kyle Jones <kyle_jones(a)wonderworks.com&gt; writes: That is what the code has been doing since a few days. It works quite well (i.e. lisp updates a copy of the tab widgets and redisplay copies that if that and the displayed version no longer match). Of course, no matter what lisp is doing, XEmacs shouldn't crash. This is not about the displayed state being update to match lisp. This about running lisp code that needs to track the state of the selected window. It must be run also inside a save-window-configuration because the code would very well be (save-window-configuration (select-window w) (recursive-edit)..) However it turns out everybody and his dog is using the (save-window-configuration (select-window w) idiom.. This is suggests two things... 1. record-buffer-hook is called way to often to do expensive things. The solution is standard. Change the hook to simply set a flag and then put the real update function at some other point that is less expensive (pre-idle-hook? There isn't a pre-redisplay-hook that I can see).[1] 2. save-window-configuration is expensive. If so much code needs to do it there is probably something missing in the api. Some functions need window arguments? Footnotes: [1] It could be you meant this in the first place. But then I disagree with the statement that is as is always been for lisp, because the appropriate hooks seem to be missing.